Post-annealing effects in two-dimensional spin system SrCuO₂ sputtered on glass substrate

Abstract

We prepared SrCuO 2 thin film by radio-frequency magnetron sputtering on glass substrate and have investigated its postannealing effects on structure and thermal conductivity. The as-sputtered film belongs to two-dimensional spin system SrCuO 2 , namely, layer-type SrCuO 2 , which has a possibility of exhibiting high, anisotropic thermal conductivity by magnetic excitation of the spins. It was found that the as-sputtered film has (001)-orientation in which the spin layers are parallel to the surface of substrate and that post-annealing results in enhancement of crystallinity of the film such as disappearance of grain boundaries, which can cause an increase in thermal conductivity.©2017 The Ceramic Society of Japan. All rights reserved.Key-words : SrCuO 2 , Sputtering, Thermal conductivity, Low-dimensional spin system, Active control of heat flow [Received December 25, 2016; Accepted February 21, 2017] The layer-type SrCuO 2 , which has been well known as a parent material of cuprate high-temperature superconductors, 1) has unique structure and characteristics:2),3) It contains alternativelystacked Sr and CuO 2 infinite layers. The CuO 2 layer exhibits a two-dimensional arrangement of antiferromagnetically-coupled spins of S = 1/2 in Cu 2+ , referred to as spin layers. Moreover, the spin structure is expected to yield high thermal conductivity parallel to the layers by the magnetic excitation. However, researches on the crystal have been limited to those concerning high-pressure synthesis and epitaxial growth on single crystal substrate. This is because the crystal belongs to a high pressure phase and accordingly is instable in ambient air.