摘要
反铁磁体/反铁磁材料因其独特的磁性质和在信息存储、自旋电子学和量子计算等领域的潜在应用前景而备受关注.然而,由于其内部相邻自旋方向相反排列,导致宏观磁化强度为零,这使得反铁磁体中磁有序的探测和表征极具挑战性.光学二次谐波产生(second harmonic generation,SHG)技术作为一种高灵敏度、非侵入性的表征手段,能够高效地探测反铁磁体系的空间反演对称破缺、自旋排列及其相变行为,现已成为探测表征反铁磁体物性的重要工具.本文综述了光学SHG技术在反铁磁性研究中的应用,包括其基本原理、实验方法以及在不同反铁磁材料系统(如氧化铬、铁酸铋和二维体系等)中的应用实例.特别关注了SHG技术如何揭示反铁磁体的相变特性、自旋排列、磁畴结构、磁电耦合效应以及在外场作用下的动态响应等.通过这些探讨,本文旨在突出SHG技术在反铁磁微观机理研究领域的广泛应用前景和巨大优势.
Antiferromagnets have garnered significant attention due to their unique magnetic properties and promising application prospects in the fields of information storage,spintronics,and quantum computing.Unlike ferromagnetic materials,where the magnetic moments of adjacent atoms align parallel,antiferromagnetic materials exhibit an antiparallel alignment of adjacent spins.This results in a net magnetic moment of zero in an ideal case and a property that eliminates stray magnetic fields,offering advantages for high-density magnetic storage and spintronic devices.However,the lack of a nonzero net magnetic moment also makes the detecting and characterizing of the antiferromagnetic order exceptionally challenging using conventional techniques.The search for effective methods to probe the intricate properties of antiferromagnetic materials has thus become a critical topic of modern physics.Optical second harmonic generation(SHG)has emerged as a powerful tool for characterizing antiferromagnetic materials.As a nonlinear optical process,SHG involves two photons combining into one with twice the photon frequency,which is a phenomenon sensitive to asymmetry properties such as spatial inversion symmetry breaking.This sensitivity makes SHG ideal for studying small-scale or delicate materials,including thin films and two-dimensional(2D)systems,positioning it as a key method for investigating antiferromagnetic properties and dynamics.One primary application of SHG is characterizing spatial inversion symmetry breaking induced by antiferromagnetic order.Polarization-dependent SHG signals provide insights into both the material symmetry and the spin configurations.This is particularly useful for materials like chromium oxide and bismuth ferrite,which exhibit intricate antiferromagnetic structures.SHG also excels in probing spin dynamics and phase transitions.By tracking the variation of symmetry and spin structures during phase transitions,such as from paramagnetic to antiferromagnetic,SHG can reveal the phase transition temperatures and mechanisms.Time-resolved SHG experiments can monitor ultrafast spin dynamics with femtosecond resolution,capturing real-time evolution under external perturbations.Another significant application is visualizing magnetic domain structures and magnetoelectric coupling effects.Conventional methods struggle to detect antiferromagnetic domains due to their zero net magnetic moment,but the sensitivity of SHG to local symmetry allows detailed antiferromagnetic domain imaging.For instance,SHG microscopy has mapped magnetic domains in bismuth ferrite thin films,revealing domain configurations and their responses to electric or magnetic fields—Insights crucial for optimizing multiferroic materials.The exploration of 2D antiferromagnetic materials,such as CrI3 and MnPS3,further underscores the versatility of SHG technology.These materials exhibit unique magnetic behaviors and strong spinlattice coupling due to reduced dimensionality.SHG has identified their distinctive properties,including phase transitions and responses to external fields like magnetic and optical excitation.In summary,SHG technology offers a versatile and sensitive approach for studying antiferromagnetic materials.Due to its ability to probe spatial inversion symmetry breaking,spin dynamics,phase transitions,and magnetic domain structures,SHG has become an indispensable tool for unraveling the complexity of antiferromagnetic order.Future advancements in SHG experimental techniques,such as higher spatial and temporal resolution and the integration with complementary methods,are expected to further enrich its applications.As researchers continue uncovering the micro-mechanisms of antiferromagnetism,SHG will play a pivotal role in advancing both fundamental understanding and technological applications in this exciting field.
作者
徐帅
金奎娟
Shuai Xu;Kui-Juan Jin(Beijing National Laboratory for Condensed Matter Physics,Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;School of Physical Sciences,University of Chinese Academy of Sciences,Beijing 100049,China)
出处
《科学通报》
北大核心
2025年第7期799-806,共8页
Chinese Science Bulletin
基金
国家重点研发计划(2019YFA0308500)
中国科学院战略性先导科技专项(B类)(XDB33030200)
中国博士后创新人才支持计划(BX20240409)
中国博士后科学基金(2024M763507)资助。
关键词
光学二次谐波产生
反铁磁序
空间反演对称性破缺
相变
物态调控
optical second harmonic generation
antiferromagnetic order
spatial inversion symmetry breaking
phase transition
manipulation of physical properties
