EPJ B Highlight - Uncovering the magnetic responses of anisotropic semimetals

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Published on 14 July 2025

Calculations show that magnetic fields can alter the responses of anisotropic 2D semimetals to electric fields and temperature gradients – but only when applied perpendicular to the material’s plane

For solid-state physicists, graphene has become a posterchild of 2D semimetals: materials whose electronic structures fall between those of a metal and a semiconductor. Owing to the honeycomb structure of its carbon atoms, graphene hosts an orderly arrangement of Dirac cones – pairs of opposite-facing, cone-shaped energy bands that touch at a single point. Immediately surrounding such a point, electron energy varies linearly with momentum, just like for massless particles such as photons – leading to exotic and often useful electronic properties.

Through a new paper published in EPJ B, Ipsita Mandal at the Shiv Nadar Institution of Eminence, India, presents fresh calculations of how these properties vary in the presence of magnetic fields, particularly when 2D semimetals are structurally distorted. Her results show that these materials’ electrical and thermal responses are affected only when the magnetic field is oriented perpendicular to the 2D plane. This finding offers deeper insight into the electronic behaviour of semimetals – potentially broadening their already wide range of technological applications.

When a 2D semimetal is subjected to uniaxial strain or pressure, its Dirac cones become stretched and tilted. This distortion creates anisotropic behaviour, meaning the speeds of electrons in the highest occupied state will vary depending on their direction of motion.

Mandal's study explores how such anisotropic semimetals respond to applied electric fields and temperature gradients – both in the presence and absence of a magnetic field. To do so, she used a semiclassical Boltzmann approach that incorporates key quantum properties of electrons. Her analysis revealed that the magnetic field’s influence emerges only when it points out of the material’s plane, not within it.

By uncovering how directional strain and magnetic fields interplay in 2D semimetals, Mandal’s findings could help researchers better understand how materials like graphene behave under external influences – and how to harness these effects in future technologies.