Magnetic field-induced ferroelectricity in S = 1/2 kagome staircase compound PbCu3TeO7
Magnetic field-induced ferroelectricity in S = 1/2 kagome staircase compound PbCu3TeO7
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DOI：
10.1038/s41535-018-0117-0
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发表时间：
2018-09
影响因子：
5.7
通讯作者：
Kyongjun Yoo;B. Koteswararao;Jeonghun Kang;A. Shahee;Woohyun Nam;F. Balakirev;V. Zapf;N. Harrison-
中科院分区：
文献类型：
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作者：
Kyongjun Yoo;B. Koteswararao;Jeonghun Kang;A. Shahee;Woohyun Nam;F. Balakirev;V. Zapf;N. Harrison-
ni3v2o8是一种典型的多铁性材料，具有s = 1 （Ni2+）自旋的kagome阶梯结构，其自旋有序与铁电性之间的复杂相互作用已经被研究了十多年。在这里，我们报道了一种新的kagome阶梯化合物pbcu3teo7，它具有Cu2+(S= 1/2)自旋，具有两个nsamel温度atTN1= 36k和tn2 = 24k，以及磁场(H)诱导的电极化(P)低于tn2。在高达60 T的磁场中，热释电和磁电电流测量表明，当h ||≤8.3 T时，自旋触发器跃迁诱导出横向的||，其量级为15µC/m2。此外，对于具有p //H//a的平行结构，会发生两次自旋-触发器跃迁，第一次发生在~ 16 T， p //不为14 μ C/m2，第二次发生在~ 38 T，此时epp消失。基于12种主要交换相互作用的蒙特卡罗模拟揭示了沿tn1以下的b轴发生正弦振幅调制，而在tn2以下的ac平面发生不相称的，适当的螺旋型自旋顺序。仿真结果表明，p //和h //下的自旋翻转转变形成ab平面型螺旋序，而h //的连续两次自旋翻转转变形成ab和bc平面的螺旋序。基于实验和理论结果，我们建立了两个方向的磁场感应磁相图和电相图，证明了扭曲的kagome楼梯结构具有相互竞争的层间相互作用和提升的挫败感，产生了大量不同的s = 1/2自旋的非共线自旋织构，从而诱导了电极化。
Ni3V2O8is an archetypical multiferroic material with a kagome staircase structure ofS= 1 (Ni2+) spins whose complex interplay between spin ordering and ferroelectricity has been studied for more than a decade. Here, we report a new kagome staircase compound PbCu3TeO7with Cu2+(S= 1/2) spins that exhibits two Néel temperatures atTN1= 36 K andTN2= 24 K, and a magnetic field (H)-induced electric polarization (P) belowTN2. Pyroelectric and magnetoelectric current measurements in magnetic fields up to 60 T reveal that forH||cof ~ 8.3 T, a spin-flop transition induces a transverseP||awith a magnitude of 15 µC/m2belowTN2. Furthermore, for a parallel configuration withP//H//a, two spin-flop transitions occur, the first at ~ 16 T withP//aof 14 µC/m2, and the second at ~ 38 T, wherePdisappears. Monte Carlo simulations based on 12 major exchange interactions uncover that a sinusoidal amplitude modulation of the spins occurs along theb-axis belowTN1and an incommensurate, proper screw-type spin order occurs in theac-plane belowTN2. The simulation results show thatP//aunderH//cstems from a spin-flop transition facilitating anab-plane-type spiral order, while the two successive spin-flop transitions forH//aresult in spiral spin orders in theab- andbc-planes. Based on the experimental and theoretical results, we establish field-induced magnetic and electric phase diagrams for the twoHdirections, demonstrating that the distorted kagome staircase structure with competing intra–interlayer interactions and lifted frustration creates a plethora of different noncollinear spin textures ofS= 1/2 spins that in turn induce electric polarization.