Negative Zero-Field-Cooled Magnetization in YMn_0.5Cr_0.5O₃due to Giant Coercivity and Trapped Field

Abstract

We report an intensive study on negative magnetization under zero-field-cooled (ZFC) mode in YMnCrO polycrystalline samples. It has been found that the magnetization reversal in ZFC measurements is strongly related to a giant coercivity of the oxide. The giant coercivity may result from the cooperative effect of magnetocrystalline anisotropy and the Dzyaloshinsky-Moriya interaction, especially at temperatures below 10 K. By fitting the high-temperature paramagnetic data under nominal zero field, the value of the trapped field in a superconducting magnet has been derived to be around several Oe, which further demonstrates that the negative ZFC magnetization is an artifact caused by negative trapped field in combination with the giant coercivity. Consequently, we suggest that one has to be cautious of trapped field in superconducting magnets in understanding negative ZFC magnetization, especially in "hard" magnetic samples.

High-Pressure Synthesis, Structures, and Properties of Trivalent A-Site-Ordered Quadruple Perovskites RMn7O12 (R = Sm, Eu, Gd, and Tb)

“…These results demonstrate an extrinsic origin of the observed negative magnetization and show that the sample insertion procedure also plays an important role in addition to the sign of the trapped fields. 32 The effect of the sample insertion procedure on ZFC curves was also observed in YVO3+δ 33 and BiMnO3-BiCrO3 solid solutions. 34 Ac susceptibility measurements ( Figures S9-S14) show frequency-independent sharp peaks on both χ ′ vs T and χ ′′ vs T curves at TN1 that is typical for ferrimagnets and canted Figure S18)…”

“…Figure 7b). Because these effects have attracted a lot of attention recently 31,32 we performed more detailed measurements on Tb0.9Mn7O11.85 ( Figure 8) and will discuss the origin of these effects in this paragraph. First, we emphasize that trapped fields inside magnetometers were always positive (PTF: positive trapped field) for these measurements as confirmed by a superconducting sample.…”

Weak ferromagnetic insulator with huge coercivity in monoclinic double perovskite La2CuIrO6

“…However, the La 2 CuIrO 6 sample shows magnetization reversal only in the ZFC mode, implying other causes in the present case. Actually, a similar negative magnetization only under ZFC mode in YMn 0.5 Cr 0.5 O 3 system has been presented very recently [44]. It has been found that the magnetization reversal in ZFC measurements is an artifact caused by negative trapped field of the superconducting magnet of the PPMS in combination with the huge coercivity.…”

Negative zero‐field‐cooled magnetization and magnetic switching in multiferroic Lu0.5Sc0.5FeO3 ceramics

“…When the applied magnetic field reaches up to 3 kOe, the magnetization changes from negative to positive, similar to that in CoCr 2 O 4 49 and YMn 0.5 Cr 0.5 O 3 . 50 It can be concluded that the negative magnetization in LSFO is related to a technical magnetization in the process as like YMn 0.5 Cr 0.5 O 3 , such as rotation or movement of magnetic domains or pinning of the domain wall, rather than the spontaneous magnetization behavior. 50 In previous report, it is believed that the negative magnetization observed in hexagonal Lu(Fe 1-x Mn x )O 3 below the T N is indicative of the weak ferromagnetism from the unquenched applied magnetic field or the pinning of canted spins near the domain wall.…”

“…50 It can be concluded that the negative magnetization in LSFO is related to a technical magnetization in the process as like YMn 0.5 Cr 0.5 O 3 , such as rotation or movement of magnetic domains or pinning of the domain wall, rather than the spontaneous magnetization behavior. 50 In previous report, it is believed that the negative magnetization observed in hexagonal Lu(Fe 1-x Mn x )O 3 below the T N is indicative of the weak ferromagnetism from the unquenched applied magnetic field or the pinning of canted spins near the domain wall. 37 Figure 3 shows the M-H curves of LSFO samples at selected temperatures between 10 and 200 K. The temperature dependence of saturated magnetization (M s ) obtained by the extrapolation of the linear part of the M-H curves to zero field and coercivity (H C ) are shown in Figure 4.…”