准一维反铁磁体BaCo$_2$V$_2$O$_8$中的反常磁热效应
Anomalous magnetocaloric effects in the quasi-one-dimensional antiferromagnet BaCo$_2$V$_2$O$_8$
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中文总结 AI 辅助
研究准一维反铁磁体BaCo$_2$V$_2$O$_8$的磁热效应，通过角分辨测量和张量网络计算发现高场下存在反常温度极小值，为磁制冷提供了新的调控思路。
中文摘要 AI 辅助
我们研究准一维类伊辛反铁磁体BaCo$_2$V$_2$O$_8$的横场热力学，其倾斜螺旋链几何结构与各向异性朗德g张量产生空间调制的塞曼耦合。角分辨磁热效应（MCE）测量显示，当磁场平行于[110]方向时，高场下存在一个靠近横场伊辛临界场的温度极小值，该极小值在磁场旋转时仅发生微弱移动。张量网络计算表明，旋转诱导的交错横场会快速降低伊辛临界场，且磁格林艾森比率在该高场温度极小值附近改变符号，与实验结果一致。我们的结果证实，显著的MCE响应可在远离伊辛临界区的区域持续存在，为通过调控量子磁体中的各向异性塞曼耦合构型实现磁制冷提供了一条途径。
英文摘要
We investigate the transverse-field thermodynamics of the quasi-one-dimensional Ising-like antiferromagnet BaCo$_2$V$_2$O$_8$, whose tilted screw-chain geometry and anisotropic Landé $g$ tensor generate spatially modulated Zeeman couplings. Angle-resolved magnetocaloric-effect (MCE) measurements reveal a high-field temperature minimum near the transverse-field Ising critical field for $H\parallel[110]$ that persists and shifts only weakly upon field rotation. Tensor-network calculations show that the rotation-induced staggered transverse field rapidly lowers the Ising critical field and that the magnetic Grüneisen ratio changes sign near the high-field temperature minimum, consistent with experiment. Our results establish that a dominant MCE response can persist away from the Ising critical region, suggesting a route to magnetic cooling by tailoring anisotropic Zeeman-coupling configurations in quantum magnets.
