Phase transitions in single-crystalline magnetoelectric LiCoPO4

Abstract

Specific heat, magnetic torque, and magnetization studies of LiCoPO4 olivine are presented. They show that a unique set of physical properties of LiCoPO4 leads to the appearance of features characteristic of two-dimensional Ising systems near the Ne´el temperature TN = 21.6 K and to the appearance of an uncommon effect of the influence of a magnetic field on the magnetocrystalline anisotropy. The latter effect manifests itself as a first-order transition, discovered at ∼9 K, induced by a magnetic field of 8 T. The physical nature of this transition was explained, and a model describing experimental dependences satisfactorily was proposed

In Situ Studies and Magnetic Properties of the Cmcm Polymorph of LiCoPO4 with a Hierarchical Dumbbell-Like Morphology Synthesized by Easy Single-Step Polyol Synthesis

“…As seen in Table 2, the values of the magnetic moments are slightly higher in comparison to the ones reported for high spin octahedral cobalt (II) complexes (4.7 to 5.2 µ B ) [38]. As reported for LCP-Pnma, the large value of the effective magnetic moment can be explained by the strongly coupled Co-O-Co superexchange interactions with Co 2+ magnetic moments or higher order interactions, such as, Co-O-P-O-Co [39,40]. On the other hand, the behavior of zero-field-cooled (ZFC) and field-cooled (FC) curves below the Néel temperature changes with the increasing magnetic field.…”

“…In literature, a weak-ferromagnetic to an antiferromagnetic state transition in LCP-Pnma was reported [41], caused by a distortion of the octahedral, formed by cobalt and oxygen atoms at low temperatures (T = 23 K); however, in order to study the origin of these metamagnetic transitions as well as the magnetic structure in different magnetic states, neutron powder diffraction experiments are required for LCP-Cmcm. value of the effective magnetic moment can be explained by the strongly coupled Co-O-Co superexchange interactions with Co 2+ magnetic moments or higher order interactions, such as, Co-O-P-O-Co [39,40]. On the other hand, the behavior of zero-field-cooled (ZFC) and field-cooled (FC) curves below the Néel temperature changes with the increasing magnetic field.…”

Recent progress in the thermodynamics of ferrotoroidic materials

“…LiCoPO 4 crystallizes in the orthorhombic P nma olivine structure [37,38]. It displays unique properties including large linear magnetoelectric effect and large Li-ionic conductivity.…”

Magnetic order, hysteresis, and phase coexistence in magnetoelectric LiCoPO4

“…Hence, the single-ion anisotropy of the Co 2+ ions is largely axial and with the easy axis along b. Below T N = 21.6 K, LiCoPO 4 orders antiferromagnetically with spins along the easy axis in a commensurate (↑↑↓↓) arrangement [7,25]. Here, ↑ and ↓ denote spin up and down, respectively, for the ion sites in forthcoming order, i.e., in the above case spins 1 and 2 are up and spins 3 and 4 are down.…”

“…The interactions J c and J ac are weak and may differ in sign depending on the magnetic ion in question [34]. [10,11,25]. In Ref.…”