Zhang Minjie, Hu Qifeng, Huang Yuqiang, Hua Chenqiang, Cheng Man, Liu Zhou, Song Shijie, Wang Fanggui, Lu Hengzhe, He Pimo, Cao Guang-Han, Xu Zhu-An, Lu Yunhao, Yang Jinbo, Zheng Yi
Zhejiang Province Key Laboratory of Quantum Technology and Device, School of Physics, and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou, 310027, P. R. China.
State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing, 100871, P. R. China.
Small. 2023 Aug;19(33):e2300964. doi: 10.1002/smll.202300964. Epub 2023 Apr 17.
The long-range magnetic ordering in frustrated magnetic systems is stabilized by coupling magnetic moments to various degrees of freedom, for example, by enhancing magnetic anisotropy via lattice distortion. Here, the unconventional spin-lattice coupled metamagnetic properties of atomically-thin CrOCl, a van der Waals antiferromagnet with inherent magnetic frustration rooted in the staggered square lattice, are reported. Using temperature- and angle-dependent tunneling magnetoconductance (TMC), in complementary with magnetic torque and first-principles calculations, the antiferromagnetic (AFM)-to-ferrimagnetic (FiM) metamagnetic transitions (MTs) of few-layer CrOCl are revealed to be triggered by collective magnetic moment flipping rather than the established spin-flop mechanism, when external magnetic field (H) enforces a lattice reconstruction interlocked with the five-fold periodicity of the FiM phase. The spin-lattice coupled MTs are manifested by drastic jumps in TMC, which show anomalous upshifts at the transition thresholds and persist much higher above the AFM Néel temperature. While the MTs exhibit distinctive triaxial anisotropy, reflecting divergent magnetocrystalline anisotropy of the c-axis AFM ground state, the resulting FiM phase has an a-c easy plane in which the magnetization axis is freely rotated by H. At the 2D limit, such a field-tunable FiM phase may provide unique opportunities to explore exotic emergent phenomena and novel spintronics devices.
在受挫磁系统中，长程磁有序通过将磁矩与各种自由度耦合来稳定，例如，通过晶格畸变增强磁各向异性。在此，报道了原子级薄的CrOCl的非常规自旋 - 晶格耦合变磁特性，CrOCl是一种范德华反铁磁体，具有源于交错方格的固有磁挫折。利用与温度和角度相关的隧穿磁电导（TMC），并结合磁转矩和第一性原理计算，发现当外部磁场（H）促使与亚铁磁（FiM）相的五重周期性互锁的晶格重构时，几层CrOCl的反铁磁（AFM）到亚铁磁（FiM）的变磁转变（MTs）是由集体磁矩翻转触发的，而不是已确立的自旋翻转机制。自旋 - 晶格耦合的MTs表现为TMC的急剧跃升，在转变阈值处出现异常上移，并且在AFM奈尔温度以上仍保持高得多的值。虽然MTs表现出独特的三轴各向异性，反映了c轴AFM基态的不同磁晶各向异性，但所得的FiM相具有一个a - c易平面，其中磁化轴可由H自由旋转。在二维极限下，这样一个场可调的FiM相可能为探索奇异的涌现现象和新型自旋电子器件提供独特的机会。
