Abstract
The tunnel magnetoresistance (TMR) is one of the most important spintronic phenomena but its reduction at finite temperature is a severe drawback for applications. Here, we reveal a crucial determinant of the drawback, that is, the $s\text{\ensuremath{-}}d$ exchange interaction between conduction $s$ and localized $d$ electrons at interfacial ferromagnetic layers. By calculating the temperature dependence of the TMR ratio in Fe/MgO/Fe(001), we show that the obtained TMR ratio significantly decreases with increasing temperature owing to the spin-flip scattering in the ${\mathrm{\ensuremath{\Delta}}}_{1}$ state induced by the $s\text{\ensuremath{-}}d$ exchange interaction. The material dependence of the coupling constant ${J}_{sd}$ is also discussed on the basis of a nonempirical method.
Highlights
The tunnel magnetoresistance (TMR) is one of the most important spintronic phenomena but its reduction at finite temperature is a severe drawback for applications
A challenging issue is the temperature decay of the tunnel magnetoresistance (TMR) in magnetic tunnel junctions (MTJs) [Fig. 1(a)], which are used for various magnetic sensors and nonvolatile magnetic random access memories
A giant TMR ratio has been demonstrated at low temperature in various MTJs [1,2,3,4,5,6,7,8,9,10], its significant reduction with increasing temperature has been observed [3,4,5,6,7,8,9,10,11]
Summary
The tunnel magnetoresistance (TMR) is one of the most important spintronic phenomena but its reduction at finite temperature is a severe drawback for applications. In this Letter, we show that an intra-atomic s-d exchange interaction between conduction s and localized d electrons plays a significant role for the temperature decay of the TMR
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