engleski

Heat conduction in spin-gap antiferromagnets

Spin-gap antiferomagnets (SG AFMs) have a discrete spin-energy spectrum due to the existence of short-range spin correlations only. The thermal conductivity of SG AFMs is a tool that probes their spin excitations and spins-phonons interaction. A variety of phenomena are observed: for example, in various strontium-cuprates thermal conductivity strongly enhances due to the opening of the heat channel carried by either magnons or spinons. In spin-Peierls compounds the thermal conductivity exhibits rather unusual double peak features at low temperatures, explained as a finger print of the spin-phonon resonance scattering. The thermal conductivity of strongly frustrated systems also shows the existence of spin-phonon resonance at low temperatures. We present the study of the thermal transport of several SG AFMs: (i) of copper-tellurides, quasi-2D geometrically frustrated compounds with S=1/2, (b) of a "zig-zag"frustrated spin ladder system LiCu2O2 (S=1/2), and (c) quasi-2D S=1 system nickel-telluride. We find that the thermal conductivity of these systems exhibit features typical for spin-phonon resonance coupling, gradually decreasing as the dimen- sionality of the systems increase. This work was done within the SNF SCOPES project No. IB7320-111044.

spin-gap antiferromagnets; structural phase transition; heat transport

The paper was presented by Ante Bilušić.