Quasi-two-dimensional magnetism and antiferromagnetic ground state in Li2FeSiO4

作     者：W. Hergett N. Bouldi M. Jonak C. Neef C. Ritter M. Abdel-Hafiez F. Seewald H.-H. Klauss M. W. Haverkort 

作者机构：Kirchhoff Institute of Physics Heidelberg University INF 227 D-69120 Heidelberg Germany Institute for Theoretical Physics Heidelberg University D-69120 Heidelberg Germany Institut Laue-Langevin 38042 Grenoble France Physics Department Faculty of Science Fayoum University Fayoum 63514 Egypt Department of Applied Physics and Astronomy University of Sharjah P. O. Box 27272 Sharjah United Arab Emirates Institute for Solid State and Materials Physics TU Dresden D-01069 Dresden Germany 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2025年第111卷第2期

页      面：024414-024414页

核心收录：

基　　金：Deutsche Forschungsgemeinschaft  DFG  (EXC2181/1-390900948) 

主　　题：Neutron diffraction 

摘      要：Our experimental (neutron diffraction, Mössbauer spectroscopy, magnetic susceptibility, specific heat) and numerical studies on the evolution of short- and long-range magnetic order in γII−Li2FeSiO4 suggest a quasi-two-dimensional (2D) nature of magnetism. The experimental data obtained on single crystals imply long-range antiferromagnetic order below TN=17 K. A broad maximum in magnetic susceptibility χ at Tm≃28 K, observation of magnetic entropy changes up to 100 K, and anisotropy in χ are indicative of low-dimensional magnetism and suggest short-range magnetic correlations up to 200 K. Neutron diffraction shows that long-range antiferromagnetic order is characterized by the propagation vector k=(12,0,12). The ordered moment μ=2.50(2) μB/Fe, at T=1.5 K, is along the crystallographic a axis. This is consistent with the observed static hyperfine field of Bhyp=14.8(3)T by Mössbauer spectroscopy which indicates significant orbital contributions. The temperature dependence of Bhyp yields the critical exponent β=0.116(12) which is in the regime of the 2D Ising behavior. LSDA+U studies exploiting the experimental spin structure suggest dominating magnetic exchange coupling within the ac layers (i.e., J3≃−6 K and J6≃−2 K) while interlayer coupling is much smaller and partly frustrated. This confirms the 2D nature of magnetism and is in full agreement with the experimental findings.