Magnetothermal Transport in Spin-Ladder Systems

Ofer Shlagman; Efrat Shimshoni

doi:10.1103/PhysRevB.86.075442

paper

Magnetothermal Transport in Spin-Ladder Systems

arXiv:1205.5962 · doi:10.1103/PhysRevB.86.075442

Abstract

We study a theoretical model for the magnetothermal conductivity of a spin-1/2 ladder with low exchange coupling ( $J ≪ Θ_{D}$ ) subject to a strong magnetic field $B$ . Our theory for the thermal transport accounts for the contribution of spinons coupled to lattice phonon modes in the one-dimensional lattice. We employ a mapping of the ladder Hamiltonian onto an XXZ spin-chain in a weaker effective field B_{eff}=B-B_{0} $, w h er e$ B_{0}=(B_{c1}+B_{c2})/2 $cor r es p o n d s t o ha l f - f i l l in g o f t h es p in o nban d . T hi s p r o v i d es a l o w - e n er g y t h eor y f or t h es p in o n e x c i t a t i o n s an d t h e i r co u pl in g t o t h e p h o n o n s . T h eco u pl in g o f a co u s t i c l o n g i t u d ina l p h o n o n s t os p in o n s g i v esr i se t o h y b r i d i z a t i o n o f s p in o n s an d p h o n o n s, an d p r o v i d es an e nhan ce d$ B $- d e p e n d an t sc a tt er in g o f p h o n o n so n s p in o n s . U s in g am e m or y ma t r i x a pp r o a c h, w es h o w t ha tt h e in t er pl a y b e tw ee n se v er a l sc a tt er in g m ec hani s m s, nam e l y : u mk l a pp, d i sor d er an d p h o n o n - s p in o n co l l i s i o n s, d o mina t es t h er e l a x a t i o n o f h e a t c u r r e n t . T hi sy i e l d s ma g n e t o t h er ma l e f f ec t s t ha t a r e q u a l i t a t i v e l y co n s i s t e n tw i t h t h e t h er ma l co n d u c t i v i t y m e a s u r e m e n t s in t h es p in - 1/2 l a dd er co m p o u n d$ {\rm Br_4(C_5H_{12}N)_2}$ (BPCB).

14 pages, 4 figures

References in corpus (6)

Cited by in corpus (1)

Plaquette Order in a Dimerized Frustrated Spin-Ladder