Magnetization dependent tunneling conductance of ferromagnetic barriers

Many standard techniques for investigating magnetic properties in the bulk are ill suited to atomically thin van der Waals materials. Here, Wang et al take a prototypical van der Waals ferromagnet, Chromium Bromide, and show how tunneling conductance can elucidate the material magnetic properties. Recent experiments on van der Waals antiferromagnets have shown that measuring the temperature (T) and magnetic field (H) dependence of the conductance allows their magnetic phase diagram to be mapped. Similarly, experiments on ferromagnetic CrBr3 barriers enabled the Curie temperature to be determined at H = 0, but a precise interpretation of the magnetoconductance data at H not equal 0 is conceptually more complex, because at finite H there is no well-defined phase boundary. Here we perform systematic transport measurements on CrBr3 barriers and show that the tunneling magnetoconductance depends on H and T exclusively through the magnetization M(H, T) over the entire temperature range investigated. The phenomenon is reproduced by the spin-dependent Fowler-Nordheim model for tunneling, and is a direct manifestation of the spin splitting of the CrBr3 conduction band. Our analysis unveils a new approach to probe quantitatively different properties of atomically thin ferromagnetic insulators related to their magnetization by performing simple conductance measurements.

Automated summary

This study shows how tunneling conductance can elucidate the material magnetic properties in atomically thin van der Waals materials. By measuring the temperature and magnetic field dependence of the conductance, the magnetic phase diagram of van der Waals materials can be mapped. The tunneling magnetoconductance in CrBr3 is found to depend exclusively on the magnetization M(H, T) over the entire temperature range, revealing a new approach to probe different properties of atomically thin ferromagnetic insulators related to their magnetization.