daniel andreica - Academia.edu (original) (raw)
Conference Presentations by daniel andreica
muSR under pressure and high magnetic fields.
Papers by daniel andreica
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2016
Journal of Physics: Condensed Matter, 2003
We report on measurements of the Knight shift K and spin–lattice relaxation rate λ of positive mu... more We report on measurements of the Knight shift K and spin–lattice relaxation rate λ of positive muons (μ+) implanted in cubic CeAg, a compound which is known to possess ferromagnetic ( K) and ferroquadrupolar (TQ = 15–16 K) order. The zero field (ZF) λ implies randomly and isotropically fluctuating Ce 4f moments above TQ which show a trend to a,
Journal of Physics: Condensed Matter, 2006
Longitudinal field μSR measurements in applied fields parallel and perpendicular to the c-axis of... more Longitudinal field μSR measurements in applied fields parallel and perpendicular to the c-axis of the hexagonal heavy-fermion antiferromagnet Ce(7)Ni(3) served to monitor the 4f-spin dynamics across the magnetic phase diagram in the B-T plane, which consists of an incommensurate/commensurate antiferromagnetic (AF) section below 1.9 K/0.7 K and below an applied field B of 0.25 T, and for B along the c-axis, of a field-induced magnetic (FIM) section for B≥0.6 T and below 0.5 K. The observed μ(+) spin-lattice relaxation rates reveal persisting spin dynamics across the whole phase diagram, reflect the various phase boundaries and are interpreted to arise in the AF and FIM phases from the Ce3 sublattice (the Ce ions are located on three different sublattices) and in the intermediate phase, viewed as a short range ordered (SRO) state, also from the Ce1 and Ce2 sublattices with slower fluctuation rates. In the paramagnetic regime the Ce1 sublattice displays the slowest spin dynamics. In the FIM phase the fraction of relaxing μ(+) appears to shrink with rising B, evidencing a possible phase separation.
Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017), 2018
In this work we present a combination of zero-field and high transverse-field muon spin rotation/... more In this work we present a combination of zero-field and high transverse-field muon spin rotation/relaxation (µ + SR) measurements. The current µ + SR Knight-shift measurements clearly shows that Ca 3 Co 2 O 6 display strong spin correlations even at room-temperature. Further, several anomalies in the temperature dependent data are proposed to be connected to the onset of a quasi-onedimensional (Q1D) ferrimagnetic order. Further, we suggest that in the low-temperature regime, the Q1D ferrimagnetic order co-exist within a long-range antiferromagnetic phase, which has been confirmed by our recent neutron scattering studies.
Pressure driven magnetic order in Sr1−xCaxCo2P2 Ola Kenji Forslund, ∗ Daniel Andreica, Yasmine Sa... more Pressure driven magnetic order in Sr1−xCaxCo2P2 Ola Kenji Forslund, ∗ Daniel Andreica, Yasmine Sassa, Masaki Imai, Chishiro Michioka, Kazuyoshi Yoshimura, Zurab Guguchia, Zurab Shermadini, Rustem Khasanov, Jun Sugiyama, and Martin Månsson † Department of Applied Physics, KTH Royal Institute of Technology, SE-106 91 Stockholm, Sweden Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania Department of Physics, Chalmers University of Technology, SE-41296 Göteborg, Sweden Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan (Dated: November 24, 2021)
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2013
Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017), 2018
In order to elucidate the magnetic ground state of the cluster magnets with a half filled triangu... more In order to elucidate the magnetic ground state of the cluster magnets with a half filled triangular lattice, we have recorded zero field (ZF-) and weak transverse field (wTF-) µ + SR spectra using powder samples of Li 2 InMo 3 O 8 and Li 2 ScMo 3 O 8 down to 1.9 K. The ZF measurements at 1.9 K demonstrated the presence of static magnetic order in Li 2 InMo 3 O 8 , whereas paramagnetic nature in Li 2 ScMo 3 O 8. The wTF measurements clarified that the magnetic transition occurs at around 11 K (= T N) in Li 2 InMo 3 O 8. However, for Li 2 ScMo 3 O 8 , there is no detectable change in the ZF-and wTF-µ + SR fit-parameters in the temperature range between 60 and 1.9 K.
Na0.7CoO2 Prepared by Electrochemical Reaction Y. Sassa1,∗, I. Umegaki2, H. Nozaki2, O.K. Forslun... more Na0.7CoO2 Prepared by Electrochemical Reaction Y. Sassa1,∗, I. Umegaki2, H. Nozaki2, O.K. Forslund3, C. Delmas4, J.-C. Orain5, A. Amato5, D. Andreica6, M. Månsson3 and J. Sugiyama2 Dep. of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden Toyota Central Research & Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan Materials Physics, KTH Royal Institute of Technology, SE-16440 Stockholm Kista, Sweden ICMCB-CNRS 87, avenue Dr. A. Schweitzer, 33608 Pessac cedex, France Lab. for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania E-mail: ∗ yasmine.sassa@physics.uu.se
Bulletin of the American Physical Society, 2019
Physica Scripta, 2021
The ferromagnetic (FM) nature of the metallic LaCo2P2 was investigated with the positive muon spi... more The ferromagnetic (FM) nature of the metallic LaCo2P2 was investigated with the positive muon spin rotation, relaxation and resonance (μ+SR) technique. Transverse and zero field μ+SR measurements revealed that the compound enters a long range FM ground state at TZFC = 135.00(1) K, consistent with previous studies. Based on the reported FM structure, the internal magnetic field was computed at the muon sites, which were predicted with first principles calculations. The computed result agree well with the experimental data. Moreover, although LaCo2P2 is a paramagnet at higher temperatures T > 160 K, it enters a short range ordered (SRO) magnetic phase for T ZF C < T ≤160 K. Measurements below the vicinity of T ZF C revealed that the SRO phase co-exists with the long range FM order at temperatures 124 K ≤T ≤T ZF C. Such co-existence is an intrinsic property and may be explained by an interplay between spin and lattice degree of freedoms.
The spin-web compound Cu3TeO6, belongs to an intriguing group of materials where magnetism is gov... more The spin-web compound Cu3TeO6, belongs to an intriguing group of materials where magnetism is governed by 3d 9 copper Cu 2+ ions. This compound has been sparsely experimentally studied and we here present the first investigation of its local magnetic properties using muon-spin relaxation/rotation ( + SR). Our results show a clear long-range 3D magnetic order below TN as indicated by clear zero-field (ZF) muon-precessions. At TN = 61.7 K a very sharp transition is observed in the weak transverse-field (wTF) as well as ZF data. Contrary to suggestions by susceptibility measurements and inelastic neutron scattering, we find no evidence for either static or dynamic (on the time-scale of + SR) spin-correlations above TN.
Quantum Beam Science, 2018
Muon spin rotation ( μ SR) spectra recorded for manganese silicide MnSi and interpreted in terms ... more Muon spin rotation ( μ SR) spectra recorded for manganese silicide MnSi and interpreted in terms of a quantitative analysis constrained by symmetry arguments were recently published. The magnetic structures of MnSi in zero-field at low temperature and in the conical phase near the magnetic phase transition were shown to substantially deviate from the expected helical and conical structures. Here, we present material backing the previous results obtained in zero-field. First, from simulations of the field distributions experienced by the muons as a function of relevant parameters, we confirm the uniqueness of the initial interpretation and illustrate the remarkable complementarity of neutron scattering and μ SR for the MnSi magnetic structure determination. Second, we present the result of a μ SR experiment performed on MnSi crystallites grown in a Zn-flux and compare it with the previous data recorded with a crystal obtained from Czochralski pulling. We find the magnetic structure f...
Scientific Reports, 2019
the K 2 Cr 8 o 16 compound belongs to a series of quasi-1D compounds with intriguing magnetic pro... more the K 2 Cr 8 o 16 compound belongs to a series of quasi-1D compounds with intriguing magnetic properties that are stabilized through a high-pressure synthesis technique. In this study, a muon spin rotation, relaxation and resonance (μ + SR) technique is used to investigate the pressure dependent magnetic properties up to 25 kbar. μ + SR allows for measurements in true zero applied field and hereby access the true intrinsic material properties. As a result, a refined temperature/pressure phase diagram is presented revealing a novel low temperature/high pressure (p C1 = 21 kbar) transition from a ferromagnetic insulating to a high-pressure antiferromagnetic insulator. Finally, the current study also indicates the possible presence of a quantum critical point at p C2 ~ 33 kbar where the magnetic order in K 2 Cr 8 o 16 is expected to be fully suppressed even at T = 0 K.
Physical Chemistry Chemical Physics, 2016
We present a solid-to-solid phase transition induced by thermal treatment in a magnetic ionic liq... more We present a solid-to-solid phase transition induced by thermal treatment in a magnetic ionic liquid (MIL) which induces the modification of the magnetic properties and super-exchange pathways.
muSR under pressure and high magnetic fields.
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2016
Journal of Physics: Condensed Matter, 2003
We report on measurements of the Knight shift K and spin–lattice relaxation rate λ of positive mu... more We report on measurements of the Knight shift K and spin–lattice relaxation rate λ of positive muons (μ+) implanted in cubic CeAg, a compound which is known to possess ferromagnetic ( K) and ferroquadrupolar (TQ = 15–16 K) order. The zero field (ZF) λ implies randomly and isotropically fluctuating Ce 4f moments above TQ which show a trend to a,
Journal of Physics: Condensed Matter, 2006
Longitudinal field μSR measurements in applied fields parallel and perpendicular to the c-axis of... more Longitudinal field μSR measurements in applied fields parallel and perpendicular to the c-axis of the hexagonal heavy-fermion antiferromagnet Ce(7)Ni(3) served to monitor the 4f-spin dynamics across the magnetic phase diagram in the B-T plane, which consists of an incommensurate/commensurate antiferromagnetic (AF) section below 1.9 K/0.7 K and below an applied field B of 0.25 T, and for B along the c-axis, of a field-induced magnetic (FIM) section for B≥0.6 T and below 0.5 K. The observed μ(+) spin-lattice relaxation rates reveal persisting spin dynamics across the whole phase diagram, reflect the various phase boundaries and are interpreted to arise in the AF and FIM phases from the Ce3 sublattice (the Ce ions are located on three different sublattices) and in the intermediate phase, viewed as a short range ordered (SRO) state, also from the Ce1 and Ce2 sublattices with slower fluctuation rates. In the paramagnetic regime the Ce1 sublattice displays the slowest spin dynamics. In the FIM phase the fraction of relaxing μ(+) appears to shrink with rising B, evidencing a possible phase separation.
Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017), 2018
In this work we present a combination of zero-field and high transverse-field muon spin rotation/... more In this work we present a combination of zero-field and high transverse-field muon spin rotation/relaxation (µ + SR) measurements. The current µ + SR Knight-shift measurements clearly shows that Ca 3 Co 2 O 6 display strong spin correlations even at room-temperature. Further, several anomalies in the temperature dependent data are proposed to be connected to the onset of a quasi-onedimensional (Q1D) ferrimagnetic order. Further, we suggest that in the low-temperature regime, the Q1D ferrimagnetic order co-exist within a long-range antiferromagnetic phase, which has been confirmed by our recent neutron scattering studies.
Pressure driven magnetic order in Sr1−xCaxCo2P2 Ola Kenji Forslund, ∗ Daniel Andreica, Yasmine Sa... more Pressure driven magnetic order in Sr1−xCaxCo2P2 Ola Kenji Forslund, ∗ Daniel Andreica, Yasmine Sassa, Masaki Imai, Chishiro Michioka, Kazuyoshi Yoshimura, Zurab Guguchia, Zurab Shermadini, Rustem Khasanov, Jun Sugiyama, and Martin Månsson † Department of Applied Physics, KTH Royal Institute of Technology, SE-106 91 Stockholm, Sweden Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania Department of Physics, Chalmers University of Technology, SE-41296 Göteborg, Sweden Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502 Japan Laboratory for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Neutron Science and Technology Center, Comprehensive Research Organization for Science and Society (CROSS), Tokai, Ibaraki 319-1106, Japan (Dated: November 24, 2021)
Meeting Abstracts of the Physical Society of Japan (Nihon Butsuri Gakkai koen gaiyoshu), 2013
Proceedings of the 14th International Conference on Muon Spin Rotation, Relaxation and Resonance (μSR2017), 2018
In order to elucidate the magnetic ground state of the cluster magnets with a half filled triangu... more In order to elucidate the magnetic ground state of the cluster magnets with a half filled triangular lattice, we have recorded zero field (ZF-) and weak transverse field (wTF-) µ + SR spectra using powder samples of Li 2 InMo 3 O 8 and Li 2 ScMo 3 O 8 down to 1.9 K. The ZF measurements at 1.9 K demonstrated the presence of static magnetic order in Li 2 InMo 3 O 8 , whereas paramagnetic nature in Li 2 ScMo 3 O 8. The wTF measurements clarified that the magnetic transition occurs at around 11 K (= T N) in Li 2 InMo 3 O 8. However, for Li 2 ScMo 3 O 8 , there is no detectable change in the ZF-and wTF-µ + SR fit-parameters in the temperature range between 60 and 1.9 K.
Na0.7CoO2 Prepared by Electrochemical Reaction Y. Sassa1,∗, I. Umegaki2, H. Nozaki2, O.K. Forslun... more Na0.7CoO2 Prepared by Electrochemical Reaction Y. Sassa1,∗, I. Umegaki2, H. Nozaki2, O.K. Forslund3, C. Delmas4, J.-C. Orain5, A. Amato5, D. Andreica6, M. Månsson3 and J. Sugiyama2 Dep. of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden Toyota Central Research & Development Laboratories, Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192, Japan Materials Physics, KTH Royal Institute of Technology, SE-16440 Stockholm Kista, Sweden ICMCB-CNRS 87, avenue Dr. A. Schweitzer, 33608 Pessac cedex, France Lab. for Muon Spin Spectroscopy, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland Faculty of Physics, Babes-Bolyai University, 400084 Cluj-Napoca, Romania E-mail: ∗ yasmine.sassa@physics.uu.se
Bulletin of the American Physical Society, 2019
Physica Scripta, 2021
The ferromagnetic (FM) nature of the metallic LaCo2P2 was investigated with the positive muon spi... more The ferromagnetic (FM) nature of the metallic LaCo2P2 was investigated with the positive muon spin rotation, relaxation and resonance (μ+SR) technique. Transverse and zero field μ+SR measurements revealed that the compound enters a long range FM ground state at TZFC = 135.00(1) K, consistent with previous studies. Based on the reported FM structure, the internal magnetic field was computed at the muon sites, which were predicted with first principles calculations. The computed result agree well with the experimental data. Moreover, although LaCo2P2 is a paramagnet at higher temperatures T > 160 K, it enters a short range ordered (SRO) magnetic phase for T ZF C < T ≤160 K. Measurements below the vicinity of T ZF C revealed that the SRO phase co-exists with the long range FM order at temperatures 124 K ≤T ≤T ZF C. Such co-existence is an intrinsic property and may be explained by an interplay between spin and lattice degree of freedoms.
The spin-web compound Cu3TeO6, belongs to an intriguing group of materials where magnetism is gov... more The spin-web compound Cu3TeO6, belongs to an intriguing group of materials where magnetism is governed by 3d 9 copper Cu 2+ ions. This compound has been sparsely experimentally studied and we here present the first investigation of its local magnetic properties using muon-spin relaxation/rotation ( + SR). Our results show a clear long-range 3D magnetic order below TN as indicated by clear zero-field (ZF) muon-precessions. At TN = 61.7 K a very sharp transition is observed in the weak transverse-field (wTF) as well as ZF data. Contrary to suggestions by susceptibility measurements and inelastic neutron scattering, we find no evidence for either static or dynamic (on the time-scale of + SR) spin-correlations above TN.
Quantum Beam Science, 2018
Muon spin rotation ( μ SR) spectra recorded for manganese silicide MnSi and interpreted in terms ... more Muon spin rotation ( μ SR) spectra recorded for manganese silicide MnSi and interpreted in terms of a quantitative analysis constrained by symmetry arguments were recently published. The magnetic structures of MnSi in zero-field at low temperature and in the conical phase near the magnetic phase transition were shown to substantially deviate from the expected helical and conical structures. Here, we present material backing the previous results obtained in zero-field. First, from simulations of the field distributions experienced by the muons as a function of relevant parameters, we confirm the uniqueness of the initial interpretation and illustrate the remarkable complementarity of neutron scattering and μ SR for the MnSi magnetic structure determination. Second, we present the result of a μ SR experiment performed on MnSi crystallites grown in a Zn-flux and compare it with the previous data recorded with a crystal obtained from Czochralski pulling. We find the magnetic structure f...
Scientific Reports, 2019
the K 2 Cr 8 o 16 compound belongs to a series of quasi-1D compounds with intriguing magnetic pro... more the K 2 Cr 8 o 16 compound belongs to a series of quasi-1D compounds with intriguing magnetic properties that are stabilized through a high-pressure synthesis technique. In this study, a muon spin rotation, relaxation and resonance (μ + SR) technique is used to investigate the pressure dependent magnetic properties up to 25 kbar. μ + SR allows for measurements in true zero applied field and hereby access the true intrinsic material properties. As a result, a refined temperature/pressure phase diagram is presented revealing a novel low temperature/high pressure (p C1 = 21 kbar) transition from a ferromagnetic insulating to a high-pressure antiferromagnetic insulator. Finally, the current study also indicates the possible presence of a quantum critical point at p C2 ~ 33 kbar where the magnetic order in K 2 Cr 8 o 16 is expected to be fully suppressed even at T = 0 K.
Physical Chemistry Chemical Physics, 2016
We present a solid-to-solid phase transition induced by thermal treatment in a magnetic ionic liq... more We present a solid-to-solid phase transition induced by thermal treatment in a magnetic ionic liquid (MIL) which induces the modification of the magnetic properties and super-exchange pathways.
![Research paper thumbnail of Low Temperature Magnetic Ordering of the Magnetic Ionic Plastic Crystal, Choline[FeCl 4 ]](https://attachments.academia-assets.com/93618389/thumbnails/1.jpg)
](Journal of Physics: Conference Series, 2015
We report on the nature of the low temperature magnetic ordering of a magnetic ionic plastic crys... more We report on the nature of the low temperature magnetic ordering of a magnetic ionic plastic crystal, Choline[FeCl4]. This investigation was carried out using heat capacity measurements, neutron diffraction experiments and muon spin relaxation (μSR) spectroscopy. The calorimetric measurements show the onset of an unusual magnetic ordering below 4 K with a possible second magnetic phase transition below 2 K. Low temperature neutron diffraction data reveal a three dimensional antiferromagnetic ordering at 2 K compatible with the previous magnetometry results. The analysis of μSR spectra indicates a magnetic phase transition below 2.2 K. At 1.6 K, the analysis of the shape of the μSR spectra suggests the existence of an additional magnetic phase with features of a possible incommensurate magnetic structure.