# Spin and charge thermopower effects in the ferromagnetic graphene junction

## Abstract

Using wave function matching approach and employing the Landauer-Buttiker formula, a ferromagnetic graphene junction with temperature gradient across the system is studied. We calculate the thermally induced charge and spin current as well as the thermoelectric voltage (Seebeck effect) in the linear and nonlinear regimes. Our calculation revealed that due to the electron-hole symmetry, the charge Seebeck coefficient is, for an undoped magnetic graphene, an odd function of chemical potential while the spin Seebeck coefficient is an even function regardless of the temperature gradient and junction length. We have also found with an accurate tuning external parameter, namely, the exchange filed and gate voltage, the temperature gradient across the junction drives a pure spin current without accompanying the charge current. Another important characteristic of thermoelectric transport, thermally induced current in the nonlinear regime, is examined. It would be our main finding that with increasing thermal gradient applied to the junction the spin and charge thermovoltages decrease and even become zero for non zero temperature bias.

- Authors:

- Department of Physics, Sari Branch, Islamic Azad University, Sari (Iran, Islamic Republic of)
- (IBS), Daejeon (Korea, Republic of)
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon (Korea, Republic of)

- Publication Date:

- OSTI Identifier:
- 22598878

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Applied Physics; Journal Volume: 120; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ELECTRIC POTENTIAL; ELECTRONS; FERROMAGNETIC MATERIALS; GRAPHENE; HOLES; JOINTS; LENGTH; NONLINEAR PROBLEMS; SEEBECK EFFECT; SPIN; TEMPERATURE GRADIENTS; WAVE FUNCTIONS

### Citation Formats

```
Vahedi, Javad, E-mail: javahedi@gmail.com, Center for Theoretical Physics of Complex Systems, Institute for Basic Science, and Barimani, Fattaneh.
```*Spin and charge thermopower effects in the ferromagnetic graphene junction*. United States: N. p., 2016.
Web. doi:10.1063/1.4961093.

```
Vahedi, Javad, E-mail: javahedi@gmail.com, Center for Theoretical Physics of Complex Systems, Institute for Basic Science, & Barimani, Fattaneh.
```*Spin and charge thermopower effects in the ferromagnetic graphene junction*. United States. doi:10.1063/1.4961093.

```
Vahedi, Javad, E-mail: javahedi@gmail.com, Center for Theoretical Physics of Complex Systems, Institute for Basic Science, and Barimani, Fattaneh. Sun .
"Spin and charge thermopower effects in the ferromagnetic graphene junction". United States.
doi:10.1063/1.4961093.
```

```
@article{osti_22598878,
```

title = {Spin and charge thermopower effects in the ferromagnetic graphene junction},

author = {Vahedi, Javad, E-mail: javahedi@gmail.com and Center for Theoretical Physics of Complex Systems, Institute for Basic Science and Barimani, Fattaneh},

abstractNote = {Using wave function matching approach and employing the Landauer-Buttiker formula, a ferromagnetic graphene junction with temperature gradient across the system is studied. We calculate the thermally induced charge and spin current as well as the thermoelectric voltage (Seebeck effect) in the linear and nonlinear regimes. Our calculation revealed that due to the electron-hole symmetry, the charge Seebeck coefficient is, for an undoped magnetic graphene, an odd function of chemical potential while the spin Seebeck coefficient is an even function regardless of the temperature gradient and junction length. We have also found with an accurate tuning external parameter, namely, the exchange filed and gate voltage, the temperature gradient across the junction drives a pure spin current without accompanying the charge current. Another important characteristic of thermoelectric transport, thermally induced current in the nonlinear regime, is examined. It would be our main finding that with increasing thermal gradient applied to the junction the spin and charge thermovoltages decrease and even become zero for non zero temperature bias.},

doi = {10.1063/1.4961093},

journal = {Journal of Applied Physics},

number = 8,

volume = 120,

place = {United States},

year = {Sun Aug 28 00:00:00 EDT 2016},

month = {Sun Aug 28 00:00:00 EDT 2016}

}