Temperature Dependence Of Low-field Magnetization Research Articles

Magnetic anomaly around orbital ordering in FeCr2S4

For polycrystalline FeCr2S4, temperature dependence of low-field magnetization shows a step-like transition around orbital ordering temperature Too ∼ 9 K. In this paper, the origin of the magnetic anomaly has been studied. We show that, with increasing magnetic field, the step-like anomaly in M–T curve is gradually suppressed. However, the external magnetic field up to 5 T has no evident influence on orbital ordering transition as revealed by specific heat measurements. Too was increased when an ultrahigh magnetic field, e.g., 14 T, has been applied. Being contrary to the inert response to magnetic field, the Too is sensitive to the variation of external pressure. M(H) curves measured at different temperatures suggest that magnetic anisotropy changes oppositely going across Too. By considering the variation of magnetocrystalline symmetry induced by orbital ordering, the magnetic anomaly around Too has been explained.

Magnetic phase diagrams of Ce1−M B2C2 (M=La and Lu)

Abstract We have synthesized the Ce 1− x La x B 2 C 2 and Ce 1− x Lu x B 2 C 2 samples and measured the temperature dependence of low-field magnetization, AC-susceptibility and specific heat. As the La or Lu concentration x increases, the Neel temperature T N decreases linearly for x ⩽0.20. However, concentration x dependence of the transition temperature changes the slope at x ∼0.25, and spin-glass transitions are observed for x ⩾0.25. The origin of the spin-glass behavior will be discussed.

Abnormal temperature dependence of low-field magnetization of FeCr2−xAlxS4

In this letter, the abnormal temperature dependence of low-field magnetization of FeCr2−xAlxS4 (0⩽x⩽0.7) is reported. In addition to a large irreversibility between zero-field-cooling (ZFC) and field-cooling (FC) magnetization for all samples, a cusp is also observed in both FC and ZFC curves for x⩽0.2. The cusp and the irreversibility are suppressed under an applied field of 0.5 T. The study of magnetic hysteresis loop reveals that this abnormal low-field magnetic behavior is closely related to coercitivity of the system. Accordingly, the abnormal magnetic behavior is explained qualitatively by taking account of large magnetic anisotropy and domain wall pinning of nonmagnetic ions.

Atomic Ordering and High-Field Magnetization in Rapidly-Quenched Ni-Mn Alloys

Magnetization measurements in steady fields of up to 300 kOe were performed for disordered and ordered Ni1-xMnx alloys prepared by rapid quenching and subsequent annealing, in order to study the correlation between atomic ordering and magnetic properties. The high-field susceptibility of the rapid-quenched samples exhibited a maximum near x = 0.25, while that for the annealed samples had a distinct minimum also near x = 0.25. Magnetization isotherms at 4.2 K for rapid-quenched samples with 0.19≤ x ≤0.34 revealed the existence of considerable hysteresis, suggesting the existence of spin-glass-like states. The temperature dependence of low-field magnetization for the same samples exhibited typical freezing behavior at low temperatures, namely, an irreversibility of field-cooled and zero-field-cooled magnetization. The freezing temperature was found to increase with increasing Mn content x.