Temperature dependence of tunneling magnetoresistance in manganite tunnel junctions

The mechanism of temperature-dependent tunneling magnetoresistance (TMR) is proposed for manganite tunnel junctions. Using the transfer Hamiltonian method, we show that the variation of the electronic spin polarization and the collective excitations of local spins at the interfaces between the insulator and the manganite electrodes are responsible for the drop of the maximum TMR ratio with increasing temperature. The theoretical result can reproduce the main characteristic feature of the experimental data in the trilayer junction structure, La0.67Sr0.33MnO3/SrTiO3/La0.67Sr0.33MnO3. [S0163-1829(99)09229-2].