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arXiv 1602.01632cond-mat.mtrl-scicond-mat.str-el
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阻挫自旋链化合物$β$ $_4$的磁各向异性

Magnetic anisotropy in the frustrated spin chain compound $β$-TeVO$_4$

F. Weickert, M. Jaime, N. Harrison, B. L. Scott, A. Leitmäe, I. Heinmaa, R. Stern, O. Janson, H. Berger, H. Rosner, A. A. Tsirlin

摘要:

报道了受抑自旋链化合物$β$-TeVO $_4$的各向同性和各向异性磁性.在零磁场中观察到的三个磁转变跟踪沿不同的结晶方向使用磁化强度,热容,和磁致伸缩测量施加的字段。在10 T以下,分别对沿$a$或$b$和沿$c$施加的磁场获得了不同的温度场图。相比之下,在18 T以上出现了几乎各向同性的高场相位,并持续到22.5 T左右出现的饱和。在低场冷却时,在$T_{\rm N1}$和$T_{\rm N2}$处朝向自旋密度波和条纹相的跃迁是第二阶的,而在$T_{\rm N3}$处朝向螺旋态的跃迁是第一阶的,并且需要晶格分量。我们的微观分析确定沮丧的$J_1-J_2$自旋链具有相当大的反铁磁链间耦合在$bc$平面和铁磁耦合沿$a$方向。这些铁磁链间耦合和链内的螺旋顺序之间的竞争是沿着$a$方向的无公度顺序的基础,如实验所观察到的。尽管螺旋状态是由链内$J_1$和$J_2$之间的竞争触发的,但由于竞争的磁各向异性,螺旋的平面不是唯一定义的。利用高分辨同步辐射衍射和$^{125}$ Te核磁共振,我们还证明了$β$-TeVO $_4$的晶体结构在低至10 K时没有发生变化,V $^{4+}$的轨道状态保持不变。

英文摘要:

Isotropic and anisotropic magnetic behavior of the frustrated spin chain compound $β$-TeVO$_4$ is reported. Three magnetic transitions observed in zero magnetic field are tracked in fields applied along different crystallographic directions using magnetization, heat capacity, and magnetostriction measurements. Qualitatively different temperature-field diagrams are obtained below 10 T for the field applied along $a$ or $b$ and along $c$, respectively. In contrast, a nearly isotropic high-field phase emerges above 18 T and persists up to the saturation that occurs around 22.5 T. Upon cooling in low fields, the transitions at $T_{\rm N1}$ and $T_{\rm N2}$ toward the spin-density-wave and stripe phases are of the second order, whereas the transition at $T_{\rm N3}$ toward the helical state is of the first order and entails a lattice component. Our microscopic analysis identifies frustrated $J_1-J_2$ spin chains with a sizable antiferromagnetic interchain coupling in the $bc$ plane and ferromagnetic couplings along the $a$ direction. The competition between these ferromagnetic interchain couplings and the helical order within the chain underlies the incommensurate order along the $a$-direction, as observed experimentally. Although a helical state is triggered by the competition between $J_1$ and $J_2$ within the chain, the plane of the helix is not uniquely defined because of competing magnetic anisotropies. Using high-resolution synchrotron diffraction and $^{125}$Te nuclear magnetic resonance, we also demonstrate that the crystal structure of $β$-TeVO$_4$ does not change down to 10 K, and the orbital state of V$^{4+}$ is preserved.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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