Magnetic phase diagram of GdNi2B2C: Two-ion magnetoelasticity and anisotropic exchange couplings

Article

关键词: SINGLE-CRYSTAL;    NEUTRON-DIFFRACTION;    METAMAGNETIC TRANSITIONS;    WEAK FERROMAGNETISM;    ANGULAR-DEPENDENCE;    HONI2B2C;    EARTH;    SUSCEPTIBILITY;    ERNI2B2C;    ORDER;   

DOI  :  10.1103/PhysRevB.67.144421

来源: SCIE

【 摘 要 】

Extensive magnetization and magnetostriction measurements were carried out on a single crystal of GdNi2B2C along the main tetragonal axes. Within the paramagnetic phase, the magnetic and strain susceptibilities revealed a weak anisotropy in the exchange couplings and two-ion tetragonal-preserving alpha-strain modes. Within the ordered phase, magnetization and magnetostriction revealed a relatively strong orthorhombic distortion mode and rich field-temperature phase diagrams. For the Hparallel to(100) phase diagram, three field-induced transformations were observed: namely, at H-D(T), related to the domain alignment; H-R(T), associated with reorientation of the moment towards the c axis; and H-S(T), defining the saturation process wherein the exchange field is completely counterbalanced. On the other hand, for the Hparallel to(001) phase diagram, only two field-induced transformations were observed: namely, at H-R(T) and H-S(T). For both phase diagrams, H-S(T) follows the relation H-S[1-(T/T-N)(2)](1/2) kOe with H-S(T-->0)=128.5(5) kOe and T-N(H=0)=19.5 K. In contrast, the thermal evolution of H-R(T) along the c axis (much simpler than along the a axis) follows the relation H-R[1-T/T-R](1/3) kOe where H-R(T-->0)=33.5(5) kOe and T-R(H=0)=13.5 K. It is emphasized that the magnetoelastic interaction and the anisotropic exchange coupling are important perturbations and therefore should be explicitly considered if a complete analysis of the magnetic properties of the borocarbides is desired.

【 授权许可】

Free