Step-like features on caloric effects of graphenes

TL;DR

This paper investigates step-like features in the electrocaloric and magnetocaloric effects of graphene nano-ribbons under combined electric and magnetic fields at low temperatures, revealing quantized behaviors linked to fundamental quantum properties.

Contribution

It introduces a detailed analysis of caloric effects in graphene under combined fields, highlighting quantized step-like features related to Landau levels and fundamental constants.

Findings

Caloric effects increase proportionally to Landau level index n+1/2.

Step-like features reveal graphene's Fermi velocity and quantum constants.

Quantization of caloric effects is observed at low temperatures.

Abstract

We considered a graphene nano-ribbon with a longitudinal electric field (along $x$ direction) and a transversal magnetic field (along $z$ direction), and then observe (i) the electrocaloric effect ruled by an applied magnetic field and (ii) the magnetocaloric effect ruled by an applied electric field. We focused our attention to the limit of low temperatures, and then observed interesting step-like features. For each filled Landau level $n$, created by the applied magnetic field, both caloric effects increase proportionally to $n+1/2$; and this step measures either important graphene properties (like Fermi velocity) or quantum fundamental quantities (like Planck constant and magnetic flux quantum).