Heat capacity in doped graphene under magnetic fields: the role of spin splitting

ESCUDERO, F; ARDENGHI, J S; JASEN, P

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Año: 2020 vol. 32

0953-8984

We study the electronic heat capacity in doped graphene under magnetic fields. The partitionfunction is calculated considering only the thermal excitations in the last occupied energylevels. Due to the large energy separation between the Landau levels (LLs) and the Zeemansplitting, at low temperatures the heat capacity is dominated by the spin excitations in the lastoccupied LL. Correspondingly the heat capacity oscillates with maximum amplitude at halffilling of each LL. At higher temperatures the inter-LLs excitations dominate the heat capacity,with maximum amplitude at full filling factors. The oscillation amplitudes are compared withthe phonon heat capacity Cp. It is shown that the spin induced heat capacity oscillations have amaximum amplitude approaching 3% of Cp, whereas for the inter-LLs excitations themaximum amplitude is only 0.1% of Cp. These amplitudes decrease in the presence ofimpurities, although the effect is appreciable if the LLs broadening is bigger than theexcitation energies.