Spin persistence in an antiferromagnetic triangular Ising lattice under a magnetic field (original) (raw)
Related papers
Dynamics of magnetization in frustrated spin-chain system Ca3Co2O6
Physical Review B, 2008
The magnetization dynamics of the triangular lattice of Ising spin chains is investigated in the framework of a two-dimensional model. The rigid chains are assumed to interact with the nearest neighboring chains, an external magnetic field, and a heat reservoir that causes the chains to change their states randomly with time. A probability of a single spin-flip process is assumed in a Glauberlike form. This technique allows describing properly the steps in the magnetization curves observed in Ca3Co2O6 and their dependence on a magnetic field sweep rate and temperature. A transition from a low-temperature to high-temperature phase is also observed.
2008
It is known that the spin-chain compound Ca3Co2O6 exhibits very interesting plateaus in the magnetization as a function of the magnetic field at low temperatures. The origin of them is still controversial. In this paper we study the thermal behavior of this compound with a single-flip Monte Carlo simulation on a triangular lattice and demonstrate the decisive influence of metastable states in the splitting of the ferrimagnetic 1/3 plateau below 10 K. We consider the [Co2O6]n chains as giant magnetic moments described by large Ising spins on planar clusters with open boundary conditions. With this simple frozen-moment model we obtain stepped magnetization curves which agree quite well with the experimental results for different sweeping rates. We describe particularly the out-of-equilibrium states that split the low-temperature 1/3 plateau into three steps. They relax thermally to the 1/3 plateau, which has long-range order at the equilibrium. Such states are further analyzed with snapshots unveiling a domain-wall structure that is responsible for the observed behavior of the 1/3 plateau. A comparison is also given of the exact results in small triangular clusters with our Monte Carlo results, providing further support for our thermal description of this compound.
Steplike Magnetization in a Spin-Chain System:Ca3Co2O6
Physical Review Letters, 2006
Due to a ferromagnetic in-chain coupling between Co 3+ ions at trigonal sites, chains Co2O6 are considered as large rigid spin moments. The antiferromagnetic Ising model on the triangular lattice is applied to describe an interchain ordering. An evolution of metastable states in a sweeping magnetic field is investigated by the single-flip technique. At the first approximation two steps in the magnetization curve and a plateau at 1/3 of the saturation magnetization are found. Four steps in magnetization are determined in high-order approximations in agreement with experimental results.
Physical Review B, 2009
It is known that the spin-chain compound Ca3Co2O6 exhibits very interesting plateaus in the magnetization as a function of the magnetic field at low temperatures. The origin of them is still controversial. In this paper we study the thermal behavior of this compound with a single-flip Monte Carlo simulation on a triangular lattice and demonstrate the decisive influence of metastable states in the splitting of the ferrimagnetic 1/3 plateau below 10 K. We consider the [Co2O6]n chains as giant magnetic moments described by large Ising spins on planar clusters with open boundary conditions. With this simple frozen-moment model we obtain stepped magnetization curves which agree quite well with the experimental results for different sweeping rates. We describe particularly the out-ofequilibrium states that split the low-temperature 1/3 plateau into three steps. They relax thermally to the 1/3 plateau, which has long-range order at the equilibrium. Such states are further analyzed with snapshots unveiling a domain-wall structure that is responsible for the observed behavior of the 1/3 plateau. A comparison is also given of the exact results in small triangular clusters with our Monte Carlo results, providing further support for our thermal description of this compound.
Quantum tunneling of the magnetization in the Ising chain compound Ca3Co2O6
Journal of Materials Chemistry, 2004
The magnetic behavior of the Ca 3 Co 2 O 6 spin chain compound is characterized by a large Ising-like character of its ferromagnetic chains, set on triangular lattice, that are antiferromagnetically coupled. At low temperature, T < 7K, the 3D antiferromagnetic state evolves towards a spin frozen state. In this temperature range, magnetic field driven magnetization of single crystals (H//chains) exhibits stepped variations. The occurrence of these steps at regular intervals of the applied magnetic field, H step =1.2T, is reminiscent of the quantum tunneling of the magnetization (QTM) of molecular based magnets. Magnetization relaxation experiments also strongly support the occurrence of this quantum phenomenon.
Relaxation and Magnetization Dynamics of Frustrated Spin-Chain Systems
Journal of Low Temperature Physics, 2010
A 3D model of the magnetization dynamics in frustrated triangular spinchain systems Ca 3 Co 2 O 6 is proposed. This model is a generalization of the 2D model developed earlier. The spins are assumed to interact with the nearest neighbors and external agency (heat reservoir and external magnetic field) that causes them to change their states randomly with time. A probability of a single spin-flip process is assumed in a Glauber-like form. The 3D model allows describing the step-like behavior of a magnetization curves experimentally observed in a strong magnetic field.
Influence of cooling field on field induced magnetic states in Ca3Co2O6 compound
Physica B: Condensed Matter, 2019
Manifold degeneracy in the zero field cooled (ZFC) state of the Ising like spin system, Ca 3 Co 2 O 6 , is progressively alleviated by magnetic field (H) at low temperature (T). Field excursion after ZFC stabilizes ferrimagnetic (FIM) state above T sf~7 K which converts to ferromagnetic (FM) state at high-H. Whereas, various metastable states have been created by H excursion of degenerate ZFC state below T sf and finally it switches to FM state. In contrast, field cooling at 5kOe supports stable FIM ordering for all temperatures in low fields, which converts to the FM state at increasingly higher-H with decrease in T. This thermomagnetic irreversibility (TMI) below~7K indicates non-ergodic nature of the ZFC state and it persists till the system fully saturates. It is obvious that both the hindered kinetics of H-T induced first order intermediate phase to FIM transformation and interplay of different interchain interactions like 1st nearest neighbor (nn) and 2nd nn with thermal energy are playing a crucial role in appearance of such type of TMI in this spin system.
2009
We report that the major features in the temperature dependence of dc and ac magnetization of a well-known spin-chain compound, Ca3Co2O6, which has been known to exhibit two complex magnetic transitions due to geometrical frustration (one near 24 K and the other near 10 K), are found to be qualitatively unaffected in its nano form synthesized by high-energy ball-milling. However, the multiple steps in isothermal magnetization - a topic of current interest in low-dimensional systems - known for the bulk form well below 10 K is absent in the nano particles. We believe that this finding will be useful to the understanding of the 'step' magnetization behavior of such spin-chain systems.
Ferromagnetic Ising Spin Chains Emerging from the Spin Ice under Magnetic Field
Journal of the Physical Society of Japan, 2003
A spin-ice compound dysprosium titanate, Dy 2 Ti 2 O 7 , is studied by specific heat measurements in magnetic fields applied along the [110] direction of the cubic unit cell. Above a magnetic field of 0.4 T a relatively sharp peak at T = 1.1 K in the specific heat appears from a broad peak associated with spin-ice freezing at low fields. This new peak is almost independent of field up to 1.5 T, while another broad, field-dependent peak is detected at higher temperature. Under magnetic field along [110] Ising spins on the pyrochlore lattice can be considered to form two orthogonal sets of chains; parallel and perpendicular to the field direction. It is suggested that these perpendicular chains behave as unique ferromagnetic Ising spin chains without long-range order, giving rise to the observed field-independent peak.