摘要
Quasi-one-dimensional(1D)antiferromagnets are known to display intriguing phenomena especially when there is a spin gap in their spin-excitation spectra.Here we demonstrate that a spin gap exists in the quasi-1D Heisenberg antiferromagnet CoTi2O5 with highly ordered Co2+/Ti4+occupation,in which the Co2+ions with S=3/2 form a 1D spin chain along the a-axis.CoTi2O5 undergoes an antiferromagnetic transition at TN~24 K and exhibits obvious anisotropic magnetic susceptibility even in the paramagnetic region.Although a gapless magnetic ground state is usually expected in a quasi-1D Heisenberg antiferromagnet with half-integer spins,by analyzing the specific heat,the thermal conductivity,and the spin-lattice relaxation rate(1/T1)as a function of temperature,we found that a spin gap is opened in the spin-excitation spectrum of CoTi2O5 around TN,manifested by the rapid decrease of magnetic specific heat to zero,the double-peak characteristic in thermal conductivity,and the exponential decay of 1/T1 below TN.Both the magnetic measurements and the first-principles calculations results indicate that there is spin-orbit coupling in CoTi2O5,which induces the magnetic anisotropy in CoTi2O5,and then opens the spin gap at low temperature.
作者
徐浩航
刘庆元
辛潮
申沁鑫
罗军
周睿
程金光
刘健
陶玲玲
刘志国
霍明学
王先杰
隋郁
Hao-Hang Xu;Qing-Yuan Liu;Chao Xin;Qin-Xin Shen;Jun Luo;Rui Zhou;Jin-Guang Cheng;Jian Liu;Ling-Ling Tao;Zhi-Guo Liu;Ming-Xue Huo;Xian-Jie Wang;Yu Sui(School of Physics,Harbin Institute of Technology,Harbin 150001,China;School of Science,Changchun University of Science and Technology,Changchun 130022,China;Beijing National Laboratory for Condensed Matter Physics,and Institute of Physics,Chinese Academy of Sciences,Beijing 100190,China;Laboratory for Space Environment and Physical Sciences,Harbin Institute of Technology,Harbin 150001,China;Southwest Institute of Applied Magnetics,Mianyang 621000,China)
基金
supported by the National Natural Science Foundation of China (Grant No. 52372003)
the Funds from Beijing National Laboratory for Condensed Matter Physics
