Field-dependent thermal and electrical transports in Cu∕CoFe multilayer

Abstract

This paper reports field-dependent thermal and electrical conductivity measurements of a 144 nm thick Cu∕CoFe giant magnetoresistive multilayer made of extremely thin periodic layers (12 and 21 Å for CoFe and Cu layers, respectively), using steady-state Joule heating and electrical resistance thermometry in suspended bridges between 300 and 380 K. Large decreases in the electrical and thermal resistivities from antiparallel to parallel alignment of the magnetization in the film, referred to as the giant magnetoresistance (GMR) and giant magnetothermal resistance (GMTR), are observed. GMR ratios of 17% and 12% and large GMTR ratios of 25% and 58% are measured at 300 and 380 K, respectively. It is concluded that different electron scattering rates for charge and heat transports in the ferromagnetic CoFe layer are responsible for the difference between the GMR and GMTR ratios. While the previous works only reported the relative change in thermal conductance due to applied magnetic field, the present manuscript reports the absolute value of the field-dependent thermal conductivity of Cu∕CoFe multilayer.