# Crystal growth and quantum oscillations in the topological chiral semimetal CoSi

## TL;DR

This study investigates the electrical transport properties of high-quality CoSi single crystals, revealing quantum oscillations, Fermi surface characteristics, and a significant Nernst effect, advancing understanding of topological chiral semimetals.

## Contribution

It provides the first observation of quantum oscillations in thermoelectrical signals of CoSi and details its Fermi surface and Berry phase, with insights into spin-orbit coupling effects.

## Key findings

- Quantum oscillations observed in thermoelectrical signals.
- Fermi surfaces around the R point characterized.
- Large Nernst effect due to phonon drag at intermediate temperatures.

## Abstract

We survey the electrical transport properties of the single-crystalline, topological chiral semimetal CoSi which was grown via different methods. High-quality CoSi single crystals were found in the growth from tellurium solution. The sample's high carrier mobility enables us to observe, for the first time, quantum oscillations (QOs) in its thermoelectrical signals. Our analysis of QOs reveals two spherical Fermi surfaces around the R point in the Brillouin zone corner. The extracted Berry phases of these electron orbits are consistent with the -2 chiral charge as reported in DFT calculations. Detailed analysis on the QOs reveals that the spin-orbit coupling induced band-splitting is less than 2 meV near the Fermi level, one order of magnitude smaller than our DFT calculation result. We also report the phonon-drag induced large Nernst effect in CoSi at intermediate temperatures.