@article{Manaparambil2023b,
title = {Giant tunnel magnetoresistance induced by thermal bias},
author = {Anand Manaparambil and Ireneusz Weymann},
url = {https://www.sciencedirect.com/science/article/pii/S0304885323009228},
doi = {10.1016/j.jmmm.2023.171272},
year = {2023},
date = {2023-12-01},
journal = {Journal of Magnetism and Magnetic Materials},
volume = {587},
pages = {171272},
abstract = {We analyze the spin-resolved transport and, in particular, the tunnel magnetoresistance of an asymmetric ferromagnetic tunnel junction with an embedded quantum dot or molecule subject to thermal and voltage bias in the nonlinear response regime. We demonstrate that such system exhibits a giant tunnel magnetoresistance effect that can be tuned by gate and bias voltages. Large values of magnetoresistance are associated with the interplay between the Kondo correlations and the ferromagnetic-contact-induced exchange field. In particular, we show that the nonequilibrium current in the parallel and antiparallel magnetic configuration of the system changes sign at different values of the voltage and thermal bias. This gives rise to giant values of magnetoresistance, the sign of which can be controlled by the applied sources.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Manaparambil2023,
title = {Nonequilibrium Seebeck effect and thermoelectric efficiency of Kondo-correlated molecular junctions},
author = {Anand Manaparambil and Ireneusz Weymann},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.107.085404},
doi = {10.1103/PhysRevB.107.085404},
year = {2023},
date = {2023-02-07},
journal = {Phys. Rev. B},
volume = {107},
pages = {085404},
abstract = {We theoretically study the nonequilibrium thermoelectric transport properties of a strongly-correlated molecule (or quantum dot) embedded in a tunnel junction. Assuming that the coupling of the molecule to the contacts is asymmetric, we determine the nonlinear current driven by the voltage and temperature gradients by using the perturbation theory. However, the subsystem consisting of the molecule strongly coupled to one of the contacts is solved by using the numerical renormalization group method, which allows for accurate description of Kondo correlations. We study the temperature gradient and voltage dependence of the nonlinear and differential Seebeck coefficients for various initial configurations of the system. In particular, we show that in the Coulomb blockade regime with singly occupied molecule, both thermopowers exhibit sign changes due to the Kondo correlations at nonequilibrium conditions. Moreover, we determine the nonlinear heat current and thermoelectric efficiency, demonstrating that the system can work as a heat engine with considerable efficiency, depending on the transport regime.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Manaparambil2022,
title = {Nonequilibrium spintronic transport through Kondo impurities},
author = {Anand Manaparambil and Andreas Weichselbaum and Jan von Delft and Ireneusz Weymann},
url = {https://journals.aps.org/prb/abstract/10.1103/PhysRevB.106.125413},
doi = {10.1103/PhysRevB.106.125413},
year = {2022},
date = {2022-09-14},
journal = {Phys. Rev. B},
volume = {106},
pages = {125413},
abstract = {In this work we analyze the nonequilibrium transport through a quantum impurity (quantum dot or molecule) attached to ferromagnetic leads by using a hybrid numerical renormalization group–time-dependent density matrix renormalization group thermofield quench approach. For this, we study the bias dependence of the differential conductance through the system, which shows a finite zero-bias peak, characteristic of the Kondo resonance and reminiscent of the equilibrium local density of states. In the nonequilibrium settings, the resonance in the differential conductance is also found to decrease with increasing the lead spin polarization. The latter induces an effective exchange field that lifts the spin degeneracy of the dot level. Therefore, as we demonstrate, the Kondo resonance can be restored by counteracting the exchange field with a finite external magnetic field applied to the system. Finally, we investigate the influence of temperature on the nonequilibrium conductance, focusing on the split Kondo resonance. Our work thus provides an accurate quantitative description of the spin-resolved transport properties relevant for quantum dots and molecules embedded in magnetic tunnel junctions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}

@article{Man2021April,
title = {Spin Seebeck effect of correlated magnetic molecules},
author = {Anand Manaparambil and Ireneusz Weymann},
url = {https://www.nature.com/articles/s41598-021-88373-7},
doi = {10.1038/s41598-021-88373-7},
year = {2021},
date = {2021-04-28},
journal = {Sci. Rep.},
volume = {11},
number = {9192},
pages = {1-15},
abstract = {In this paper we investigate the spin-resolved thermoelectric properties of strongly correlated molecular junctions in the linear response regime. The magnetic molecule is modeled by a single orbital level to which the molecular core spin is attached by an exchange interaction. Using the numerical renormalization group method we analyze the behavior of the (spin) Seebeck effect, heat conductance and figure of merit for different model parameters of the molecule. We show that the thermopower strongly depends on the strength and type of the exchange interaction as well as the molecule’s magnetic anisotropy. When the molecule is coupled to ferromagnetic leads, the thermoelectric properties reveal an interplay between the spin-resolved tunneling processes and intrinsic magnetic properties of the molecule. Moreover, in the case of finite spin accumulation in the leads, the system exhibits the spin Seebeck effect. We demonstrate that a considerable spin Seebeck effect can develop when the molecule exhibits an easy-plane magnetic anisotropy, while the sign of the spin thermopower depends on the type and magnitude of the molecule’s exchange interaction.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}