Thermal conductivity of thin insulating films determined by tunnel magneto-Seebeck effect measurements and finite-element modeling

Abstract

In general, it is difficult to access the thermal conductivity of thin insulating films experimentally just by electrical means. Here, we present a new approach utilizing the tunnel magneto-Seebeck effect (TMS) in combination with finite-element modeling (FEM). We detect the laser-induced TMS and the absolute thermovoltage of laser-heated magnetic tunnel junctions with 2.6 nm thin barriers of MgAl${}_2$O${}_4$ (MAO) and MgO, respectively. A second measurement of the absolute thermovoltage after a dielectric breakdown of the barrier grants insight into the remaining thermovoltage of the stack. Thus, the pure TMS without any parasitic Nernst contributions from the leads can be identified. In combination with FEM via COMSOL, we are able to extract values for the thermal conductivity of MAO ($0.7$ W/(K$\cdot$m)) and MgO ($5.8$ W/(K$\cdot$m)), which are in very good agreement with theoretical predictions. Our method provides a new promising way to extract the experimentally challenging parameter of the thermal conductivity of thin insulating films.

References in corpus (14)

• Spin Caloritronics
• Seebeck Effect in Magnetic Tunnel Junctions
• Tunneling magneto thermo power in magnetic tunnel junction nanopillars
• Spin caloritronics in magnetic tunnel junctions: Ab initio studies
• Large magneto-Seebeck effect in magnetic tunnel junctions with half-metallic Heusler electrodes
• Time-resolved measurement of the tunnel magneto-Seebeck effect in a single magnetic tunnel junction
• Thermal transport and non-equilibrium temperature drop across a magnetic nanostructured interface
• Determination of spin-dependent Seebeck coefficients of CoFeB/MgO/CoFeB magnetic tunnel junction nanopillars
• Comparison of laser induced and intrinsic tunnel magneto-Seebeck effect in CoFeB/MgAl${}_2$O${}_4$ and CoFeB/MgO magnetic tunnel junctions
• Tunneling magneto thermocurrent in CoFeB/MgO/CoFeB based magnetic tunnel junctions
• Enhancement of thermovoltage and tunnel magneto-Seebeck effect in CoFeB based magnetic tunnel junctions by variation of the MgAl${}_2$O${}_4$ and MgO barrier thickness
• On/off switching of bit readout in bias-enhanced tunnel magneto-Seebeck effect
• Thermal conductance of thin film YIG determined using Bayesian statistics
• Pumping laser excited spins through MgO barriers

Cited by in corpus (5)

• Spincaloritronic measurements: a round robin comparison of the longitudinal spin Seebeck effect
• Tunnel magneto-Seebeck effect
• Thermal Conductivity of Oxide Tunnel Barriers in Magnetic Tunnel Junctions Measured by Ultrafast Thermoreflectance and Magneto-optic Kerr Effect Thermometry
• Anomalous Nernst effect on the nanometer scale: Exploring three-dimensional temperature gradients in magnetic tunnel junctions
• Strain-induced enhancement of the Seebeck effect in magnetic tunneling junctions via interface resonant tunneling: Ab-initio study