Critical temperature and low-energy excitations in gapped spin systems with defects

Article

关键词: LONG-RANGE ORDER;    SOLITON LATTICE;    PEIERLS;    KCUCL3;    STATE;    ZN;   

DOI  :  10.1103/PhysRevB.103.024420

来源: SCIE

【 摘 要 】

We discuss theoretically the magnetically ordered phase induced by magnetic and nonmagnetic impurities in three-dimensional and quasi-low-dimensional systems with singlet ground states separated by a gap from excited triplet states. Using ideas of the percolation theory, we estimate the transition temperature T-N (n) to the Neel phase at a small concentration n of defects, derive the density of states of low-energy elementary excitations, and examine the contribution of these excitations to the specific heat and magnetization. Our expressions for T-N ( n) and for the specific heat describe well available experimental findings obtained in various appropriate systems: spin-1/2 dimer materials, spin-ladder compounds, spin-Peierls, and Haldane chain materials. However, our expression for T-N (n) differs considerably from many of those proposed before.

【 授权许可】

Free