Teresa Castan - Academia.edu (original) (raw)
Papers by Teresa Castan
Shape memory and superelasticity, Jul 21, 2015
We develop a combined Ginzburg-Landau/ micromagnetic model dealing with conventional and magnetic... more We develop a combined Ginzburg-Landau/ micromagnetic model dealing with conventional and magnetic shape-memory properties in ferromagnetic shapememory materials. The free energy of the system is written as the sum of structural, magnetic and magnetostructural contributions. We first analyse a mean field linearized version of the model that does not take into account longrange terms arising from elastic compatibility and demagnetization effects. This model can be solved analytically and in spite of its simplicity allows us to understand the role of the magnetostructural term in driving magnetic shape-memory effects. Numerical simulations of the full model have also been performed. They show that the model is able to reproduce magnetostructural microstructures reported in magnetic shape-memory materials such as Ni 2 MnGa as well as conventional and magnetic shape-memory behaviour.
Materials Today: Proceedings, 2015
Caloric properties rely on the reversible thermal response of a given material to changes induced... more Caloric properties rely on the reversible thermal response of a given material to changes induced by an applied field. In magnetic shape-memory materials, thanks to a strong interplay between magnetism and structure, caloric effects can be induced by application of both magnetic and mechanical (stress) fields. The study of such effects is an expanding field of research opening novel opportunities in solid state refrigeration and energy harvesting applications. In this paper we present an overview of the present state of the art of the subject. After a brief discussion of the thermodynamics of systems with magneto-structural interplay, we survey the caloric and multicaloric properties of NiMn-based Heusler materials. The conditions required for optimal caloric efficiency in cycling processes are considered. Finally, we outline some present challenges and future perspectives in this topic.
Philosophical Transactions of the Royal Society A, Aug 13, 2016
One contribution of 16 to a discussion meeting issue 'Taking the temperature of phase transitions... more One contribution of 16 to a discussion meeting issue 'Taking the temperature of phase transitions in cool materials' .
Physical review, Mar 17, 2017
We report on the multicaloric response of the Fe 49 Rh 51 alloy under the combined application of... more We report on the multicaloric response of the Fe 49 Rh 51 alloy under the combined application of hydrostatic pressure and magnetic field. Experimental data are complemented by a mean field model that takes into account the interplay between structural and magnetic degrees of freedom. A large multicaloric strength has been found for this alloy, and it is shown that a suitable combination of pressure and magnetic field enables the sign of the entropy change to be reversed and thus the multicaloric effect can be tuned from conventional to inverse. It is also shown that an extended temperature window for the multicaloric effect can be achieved by taking advantage of the coupling between structure and magnetism which enables a cross response of the alloy under the application of different external fields. Mean field calculations remarkably reproduce experimental results.
Mrs Bulletin, Apr 1, 2018
Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by ... more Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by more than one type of external field, and the resulting multicaloric effects can be large in multiferroic materials. The use of more than one driving field can permit access to larger thermal changes, with smaller field magnitudes, over wider ranges of operating temperature, while manipulating hysteresis. The thermodynamics behind multicaloric effects is well established, but only a small number of multicaloric effects have been experimentally studied to date. Here we describe the fundamentals of multicaloric effects, and discuss the performance of representative multicaloric materials. Exploiting multicaloric effects could aid the future development of cooling devices, where key challenges include energy efficiency and operating temperature span.
Physical review, Dec 13, 2019
We study the relationship between avalanche criticality and the number of orientational domains i... more We study the relationship between avalanche criticality and the number of orientational domains in ferroelastic transitions. To this end, we use a general Ginzburg-Landau model appropriate for displacive transitions of the square lattice. The model includes disorder as a quenched distribution of local transition temperatures. We focus on the square-to-rectangle and the square-to-oblique ferroelastic transitions, which have two and four orientational domains, respectively, which in turn determine the corresponding degeneracy of the ground state of the system. The phase transitions are driven by temperature under the assumption of a strict athermal behavior. That is, we assume that thermal fluctuations do not play any role. Numerical results are obtained using a purely relaxational dynamics, and it is shown that both the square-to-rectangle and the square-to-oblique transitions occur intermittently in the form of avalanches. Avalanche sizes and avalanche energies are found to display power-law distributions, which corroborates avalanche criticality. We compare and contrast the dependence of avalanche criticality on the number of orientational domains of the low-symmetry phase. It is found that the critical exponents depend on that number, in agreement with recent experimental results.
Physica Status Solidi B-basic Solid State Physics, Aug 28, 2017
We Q4 combine a Ginzburg-Landau model for a ferroelastic transition with 6 the theory of micromag... more We Q4 combine a Ginzburg-Landau model for a ferroelastic transition with 6 the theory of micromagnetism to study the magnetostructural behavior 7 leading to multicaloric effects in ferromagnetic shape memory alloys. We 8 analyze the ferroelastic transition under different conditions of temperature, 9 stress and magnetic field and establish the corresponding phase diagram. 10 On the one hand, our results show that the proper combination of both 11 fields may be used to reduce the transition hysteresis and thus improve the 12 reversibility of the related elastocaloric effects, superelasticity and stress-13 mediated magnetocaloric effects. On the other hand, the stress-free magnetic 14 field-driven and thermally driven magnetostructural evolution provides physi-15 cal insight into the low-temperature field-induced domain reorientation, from 16 which we derive strategies to modify the operational temperature ranges and 17 thus the corresponding (magnetic) shape-memory effect. 18 1. Introduction 19 Technological implementation of functional properties dis-20 played by magnetostructural materials is often hindered by 21 some fundamental drawbacks such as large required fields, 22 cycling fatigue, inappropriate operational ranges, and/or low 23 reversibility due to large hysteresis. Well-known examples are 24 the shape-memory effect and superelasticity, used in sensors, 25 actuators and other technologies, [1,2] and caloric effects, the latter 26 currently attracting great interest due to their potential in more 27 efficient, environmentally friendly solid-state cooling devices. [3,4] 28 At present, most usual methods to overcome the aforemen-29 tioned obstacles mainly consist of tuning material's properties
Philosophical Magazine, Apr 15, 2014
We provide a general thermodynamic framework to study multicaloric effects in multiferroic materi... more We provide a general thermodynamic framework to study multicaloric effects in multiferroic materials. This is applied to the case of a magnetoelectric multiferroic such as BiFeO, which is described by means of a Landau free energy with a biquadratic coupling between polarization and magnetization. We obtain a phase diagram, the isothermal entropy change and the adiabatic temperature change across different continuous and first-order phase transitions as the applied electric and magnetic fields are varied. The multicaloric effects are suitably decomposed into the corresponding electrocaloric and magnetocaloric contributions.
Physical review, Sep 24, 2021
A Ginzburg-Landau model embedded into a vibrational model is used to study the flexocaloric effec... more A Ginzburg-Landau model embedded into a vibrational model is used to study the flexocaloric effect in a beam near a ferroelastic transition. The caloric response upon bending is characterized by the isothermal entropy change and the adiabatic temperature change of the beam. We obtain a larger response relative to the strength of the applied forces at temperatures slightly above the transition temperature. It is also obtained that the maximum caloric response is almost linear with the bending angle of the beam, whereas the relation between the bending angle and the applied forces is highly nonlinear. Small hysteresis associated with the phase transition is obtained for sufficiently large bending forces due to the existence of a critical point in the temperature-stress phase diagram of the ferroelastic material. Finally, the microstructure changes with bending in the beam are consistent with previous experimental observations.
Physical review, Sep 1, 1989
Physical review, Sep 1, 1999
The degenerate Blume-Emery-Griffiths model for martensitic transformations is extended by includi... more The degenerate Blume-Emery-Griffiths model for martensitic transformations is extended by including both structural and magnetic degrees of freedom in order to elucidate premartensitic effects. Special attention is paied to the effect of the magnetoelastic coupling in Ni2MnGa. The microscopic model is constructed and justified based on the analysis of the experimentally observed strain variables and precursor phenomena. The description includes the (local) tetragonal distortion, the amplitude of the plane-modulating strain, and the magnetization. The model is solved by means of mean-field theory and Monte Carlo simulations. This last technique reveals the crucial importance of fluctuations in pretransitional effects. The results show that a variety of premartensitic effects may appear due to the magnetoelastic coupling. In the mean-field formulation this coupling is quadratic in both the modulation amplitude and the magnetization. For large values of the magnetoelastic coupling parameter we find a premartensitic first-order transition line ending in a critical point. This critical point is responsible for the existence of large premartensitic fluctuations which manifest as broad peaks in the specific heat, not always associated with a true phase transition. The main conclusion is that premartensitic effects result from the interplay between the softness of the anomalous phonon driving the modulation and the magnetoelastic coupling. In particular, the premartensitic transition occurs when such coupling is strong enough to freeze the involved mode phonon. The implication of the results in relation to the available experimental data is discussed.
APS March Meeting Abstracts, Mar 1, 2003
![Research paper thumbnail of Publisher's Note: Enhanced caloric effect induced by magnetoelastic coupling in NiMnGaCu Heusler alloys: Experimental study and theoretical analysis [Phys. Rev. B 96 , 224105 (2017)]](https://attachments.academia-assets.com/110638318/thumbnails/1.jpg)
](Physical review, Jan 25, 2018
Bulletin of the American Physical Society, Mar 5, 2018
Physical review, Feb 15, 1989
Physical review, Sep 28, 2018
No further publication processing will occur until we receive your response to this proof. Attach... more No further publication processing will occur until we receive your response to this proof. Attached is a PDF proof of your forthcoming article in PRE. Your article has 10 pages and the Accession Code is XS10277E. Please note that as part of the production process, APS converts all articles, regardless of their original source, into standardized XML that in turn is used to create the PDF and online versions of the article as well as to populate third-party systems such as Portico, Crossref, and Web of Science. We share our authors' high expectations for the fidelity of the conversion into XML and for the accuracy and appearance of the final, formatted PDF. This process works exceptionally well for the vast majority of articles; however, please check carefully all key elements of your PDF proof, particularly any equations or tables. FQ: This funding provider could not be uniquely identified during our search of the FundRef registry (or no Contract or Grant number was detected). Please check information and amend if incomplete or incorrect. Open Funder Registry: Information about an article's funding sources is now submitted to Crossref to help you comply with current or future funding agency mandates. Crossref's Open Funder Registry (https://www.crossref.org/services/funder-registry/) is the definitive registry of funding agencies. Please ensure that your acknowledgments include all sources of funding for your article following any requirements of your funding sources. Where possible, please include grant and award ids. Please carefully check the following funder information we have already extracted from your article and ensure its accuracy and completeness: MINECO (ES) AEI (US)
Springer series in materials science, 2018
Glassiness is ubiquitous in nature but it still keeps many fascinating phenomena hidden. The disc... more Glassiness is ubiquitous in nature but it still keeps many fascinating phenomena hidden. The discovery about a decade ago of glassy behavior in strain nanoclusters (the strain glass) has extended ferroic glasses to include the ferroelastic property. Here, by means of numerical modelling and comparison with experimental data in the literature, we identify disorder and anisotropy as key parameters whose interplay determines the ferroelastic behavior in alloys: While anisotropy-driven systems exhibit a normal ferroelastic transition, disorder-driven systems may result in the strain glass state. Interestingly, strain glass preserves functional properties such as the shape memory effect (SME) and superelasticity. Moreover, it exhibits hysteresis reduction and widening of operational temperature-stress range, which enhances its technological appeal. Precisely based on the occurrence of the SME, the relevance of geometrical frustration in strain glass is called into question as it might play a minor role in the freezing process. In magnetostructural systems, the multiferroic coupling could yield strain-mediated magnetic glass.
MRS Bulletin, 2018
Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by ... more Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by more than one type of external field, and the resulting multicaloric effects can be large in multiferroic materials. The use of more than one driving field can permit access to larger thermal changes, with smaller field magnitudes, over wider ranges of operating temperature, while manipulating hysteresis. The thermodynamics behind multicaloric effects is well established, but only a small number of multicaloric effects have been experimentally studied to date. Here we describe the fundamentals of multicaloric effects, and discuss the performance of representative multicaloric materials. Exploiting multicaloric effects could aid the future development of cooling devices, where key challenges include energy efficiency and operating temperature span.
Shape memory and superelasticity, Jul 21, 2015
We develop a combined Ginzburg-Landau/ micromagnetic model dealing with conventional and magnetic... more We develop a combined Ginzburg-Landau/ micromagnetic model dealing with conventional and magnetic shape-memory properties in ferromagnetic shapememory materials. The free energy of the system is written as the sum of structural, magnetic and magnetostructural contributions. We first analyse a mean field linearized version of the model that does not take into account longrange terms arising from elastic compatibility and demagnetization effects. This model can be solved analytically and in spite of its simplicity allows us to understand the role of the magnetostructural term in driving magnetic shape-memory effects. Numerical simulations of the full model have also been performed. They show that the model is able to reproduce magnetostructural microstructures reported in magnetic shape-memory materials such as Ni 2 MnGa as well as conventional and magnetic shape-memory behaviour.
Materials Today: Proceedings, 2015
Caloric properties rely on the reversible thermal response of a given material to changes induced... more Caloric properties rely on the reversible thermal response of a given material to changes induced by an applied field. In magnetic shape-memory materials, thanks to a strong interplay between magnetism and structure, caloric effects can be induced by application of both magnetic and mechanical (stress) fields. The study of such effects is an expanding field of research opening novel opportunities in solid state refrigeration and energy harvesting applications. In this paper we present an overview of the present state of the art of the subject. After a brief discussion of the thermodynamics of systems with magneto-structural interplay, we survey the caloric and multicaloric properties of NiMn-based Heusler materials. The conditions required for optimal caloric efficiency in cycling processes are considered. Finally, we outline some present challenges and future perspectives in this topic.
Philosophical Transactions of the Royal Society A, Aug 13, 2016
One contribution of 16 to a discussion meeting issue 'Taking the temperature of phase transitions... more One contribution of 16 to a discussion meeting issue 'Taking the temperature of phase transitions in cool materials' .
Physical review, Mar 17, 2017
We report on the multicaloric response of the Fe 49 Rh 51 alloy under the combined application of... more We report on the multicaloric response of the Fe 49 Rh 51 alloy under the combined application of hydrostatic pressure and magnetic field. Experimental data are complemented by a mean field model that takes into account the interplay between structural and magnetic degrees of freedom. A large multicaloric strength has been found for this alloy, and it is shown that a suitable combination of pressure and magnetic field enables the sign of the entropy change to be reversed and thus the multicaloric effect can be tuned from conventional to inverse. It is also shown that an extended temperature window for the multicaloric effect can be achieved by taking advantage of the coupling between structure and magnetism which enables a cross response of the alloy under the application of different external fields. Mean field calculations remarkably reproduce experimental results.
Mrs Bulletin, Apr 1, 2018
Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by ... more Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by more than one type of external field, and the resulting multicaloric effects can be large in multiferroic materials. The use of more than one driving field can permit access to larger thermal changes, with smaller field magnitudes, over wider ranges of operating temperature, while manipulating hysteresis. The thermodynamics behind multicaloric effects is well established, but only a small number of multicaloric effects have been experimentally studied to date. Here we describe the fundamentals of multicaloric effects, and discuss the performance of representative multicaloric materials. Exploiting multicaloric effects could aid the future development of cooling devices, where key challenges include energy efficiency and operating temperature span.
Physical review, Dec 13, 2019
We study the relationship between avalanche criticality and the number of orientational domains i... more We study the relationship between avalanche criticality and the number of orientational domains in ferroelastic transitions. To this end, we use a general Ginzburg-Landau model appropriate for displacive transitions of the square lattice. The model includes disorder as a quenched distribution of local transition temperatures. We focus on the square-to-rectangle and the square-to-oblique ferroelastic transitions, which have two and four orientational domains, respectively, which in turn determine the corresponding degeneracy of the ground state of the system. The phase transitions are driven by temperature under the assumption of a strict athermal behavior. That is, we assume that thermal fluctuations do not play any role. Numerical results are obtained using a purely relaxational dynamics, and it is shown that both the square-to-rectangle and the square-to-oblique transitions occur intermittently in the form of avalanches. Avalanche sizes and avalanche energies are found to display power-law distributions, which corroborates avalanche criticality. We compare and contrast the dependence of avalanche criticality on the number of orientational domains of the low-symmetry phase. It is found that the critical exponents depend on that number, in agreement with recent experimental results.
Physica Status Solidi B-basic Solid State Physics, Aug 28, 2017
We Q4 combine a Ginzburg-Landau model for a ferroelastic transition with 6 the theory of micromag... more We Q4 combine a Ginzburg-Landau model for a ferroelastic transition with 6 the theory of micromagnetism to study the magnetostructural behavior 7 leading to multicaloric effects in ferromagnetic shape memory alloys. We 8 analyze the ferroelastic transition under different conditions of temperature, 9 stress and magnetic field and establish the corresponding phase diagram. 10 On the one hand, our results show that the proper combination of both 11 fields may be used to reduce the transition hysteresis and thus improve the 12 reversibility of the related elastocaloric effects, superelasticity and stress-13 mediated magnetocaloric effects. On the other hand, the stress-free magnetic 14 field-driven and thermally driven magnetostructural evolution provides physi-15 cal insight into the low-temperature field-induced domain reorientation, from 16 which we derive strategies to modify the operational temperature ranges and 17 thus the corresponding (magnetic) shape-memory effect. 18 1. Introduction 19 Technological implementation of functional properties dis-20 played by magnetostructural materials is often hindered by 21 some fundamental drawbacks such as large required fields, 22 cycling fatigue, inappropriate operational ranges, and/or low 23 reversibility due to large hysteresis. Well-known examples are 24 the shape-memory effect and superelasticity, used in sensors, 25 actuators and other technologies, [1,2] and caloric effects, the latter 26 currently attracting great interest due to their potential in more 27 efficient, environmentally friendly solid-state cooling devices. [3,4] 28 At present, most usual methods to overcome the aforemen-29 tioned obstacles mainly consist of tuning material's properties
Philosophical Magazine, Apr 15, 2014
We provide a general thermodynamic framework to study multicaloric effects in multiferroic materi... more We provide a general thermodynamic framework to study multicaloric effects in multiferroic materials. This is applied to the case of a magnetoelectric multiferroic such as BiFeO, which is described by means of a Landau free energy with a biquadratic coupling between polarization and magnetization. We obtain a phase diagram, the isothermal entropy change and the adiabatic temperature change across different continuous and first-order phase transitions as the applied electric and magnetic fields are varied. The multicaloric effects are suitably decomposed into the corresponding electrocaloric and magnetocaloric contributions.
Physical review, Sep 24, 2021
A Ginzburg-Landau model embedded into a vibrational model is used to study the flexocaloric effec... more A Ginzburg-Landau model embedded into a vibrational model is used to study the flexocaloric effect in a beam near a ferroelastic transition. The caloric response upon bending is characterized by the isothermal entropy change and the adiabatic temperature change of the beam. We obtain a larger response relative to the strength of the applied forces at temperatures slightly above the transition temperature. It is also obtained that the maximum caloric response is almost linear with the bending angle of the beam, whereas the relation between the bending angle and the applied forces is highly nonlinear. Small hysteresis associated with the phase transition is obtained for sufficiently large bending forces due to the existence of a critical point in the temperature-stress phase diagram of the ferroelastic material. Finally, the microstructure changes with bending in the beam are consistent with previous experimental observations.
Physical review, Sep 1, 1989
Physical review, Sep 1, 1999
The degenerate Blume-Emery-Griffiths model for martensitic transformations is extended by includi... more The degenerate Blume-Emery-Griffiths model for martensitic transformations is extended by including both structural and magnetic degrees of freedom in order to elucidate premartensitic effects. Special attention is paied to the effect of the magnetoelastic coupling in Ni2MnGa. The microscopic model is constructed and justified based on the analysis of the experimentally observed strain variables and precursor phenomena. The description includes the (local) tetragonal distortion, the amplitude of the plane-modulating strain, and the magnetization. The model is solved by means of mean-field theory and Monte Carlo simulations. This last technique reveals the crucial importance of fluctuations in pretransitional effects. The results show that a variety of premartensitic effects may appear due to the magnetoelastic coupling. In the mean-field formulation this coupling is quadratic in both the modulation amplitude and the magnetization. For large values of the magnetoelastic coupling parameter we find a premartensitic first-order transition line ending in a critical point. This critical point is responsible for the existence of large premartensitic fluctuations which manifest as broad peaks in the specific heat, not always associated with a true phase transition. The main conclusion is that premartensitic effects result from the interplay between the softness of the anomalous phonon driving the modulation and the magnetoelastic coupling. In particular, the premartensitic transition occurs when such coupling is strong enough to freeze the involved mode phonon. The implication of the results in relation to the available experimental data is discussed.
APS March Meeting Abstracts, Mar 1, 2003
Physical review, Jan 25, 2018
Bulletin of the American Physical Society, Mar 5, 2018
Physical review, Feb 15, 1989
Physical review, Sep 28, 2018
No further publication processing will occur until we receive your response to this proof. Attach... more No further publication processing will occur until we receive your response to this proof. Attached is a PDF proof of your forthcoming article in PRE. Your article has 10 pages and the Accession Code is XS10277E. Please note that as part of the production process, APS converts all articles, regardless of their original source, into standardized XML that in turn is used to create the PDF and online versions of the article as well as to populate third-party systems such as Portico, Crossref, and Web of Science. We share our authors' high expectations for the fidelity of the conversion into XML and for the accuracy and appearance of the final, formatted PDF. This process works exceptionally well for the vast majority of articles; however, please check carefully all key elements of your PDF proof, particularly any equations or tables. FQ: This funding provider could not be uniquely identified during our search of the FundRef registry (or no Contract or Grant number was detected). Please check information and amend if incomplete or incorrect. Open Funder Registry: Information about an article's funding sources is now submitted to Crossref to help you comply with current or future funding agency mandates. Crossref's Open Funder Registry (https://www.crossref.org/services/funder-registry/) is the definitive registry of funding agencies. Please ensure that your acknowledgments include all sources of funding for your article following any requirements of your funding sources. Where possible, please include grant and award ids. Please carefully check the following funder information we have already extracted from your article and ensure its accuracy and completeness: MINECO (ES) AEI (US)
Springer series in materials science, 2018
Glassiness is ubiquitous in nature but it still keeps many fascinating phenomena hidden. The disc... more Glassiness is ubiquitous in nature but it still keeps many fascinating phenomena hidden. The discovery about a decade ago of glassy behavior in strain nanoclusters (the strain glass) has extended ferroic glasses to include the ferroelastic property. Here, by means of numerical modelling and comparison with experimental data in the literature, we identify disorder and anisotropy as key parameters whose interplay determines the ferroelastic behavior in alloys: While anisotropy-driven systems exhibit a normal ferroelastic transition, disorder-driven systems may result in the strain glass state. Interestingly, strain glass preserves functional properties such as the shape memory effect (SME) and superelasticity. Moreover, it exhibits hysteresis reduction and widening of operational temperature-stress range, which enhances its technological appeal. Precisely based on the occurrence of the SME, the relevance of geometrical frustration in strain glass is called into question as it might play a minor role in the freezing process. In magnetostructural systems, the multiferroic coupling could yield strain-mediated magnetic glass.
MRS Bulletin, 2018
Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by ... more Multicaloric materials show thermal changes that can be driven simultaneously or sequentially by more than one type of external field, and the resulting multicaloric effects can be large in multiferroic materials. The use of more than one driving field can permit access to larger thermal changes, with smaller field magnitudes, over wider ranges of operating temperature, while manipulating hysteresis. The thermodynamics behind multicaloric effects is well established, but only a small number of multicaloric effects have been experimentally studied to date. Here we describe the fundamentals of multicaloric effects, and discuss the performance of representative multicaloric materials. Exploiting multicaloric effects could aid the future development of cooling devices, where key challenges include energy efficiency and operating temperature span.