Spin-induced anomalous magnetoresistance at the (100) surface of hydrogen-terminated diamond

TL;DR

This study reveals that the (100) surface of hydrogen-terminated diamond exhibits positive, spin-related magnetoresistance at low temperatures, contrasting with previous (111) surface results, highlighting the role of spin in surface conductivity.

Contribution

The paper demonstrates the spin-induced anomalous magnetoresistance in (100) diamond surfaces, a novel finding differing from prior (111) surface studies, emphasizing the importance of spin effects.

Findings

Magnetoresistance is positive between 2-10 K and -7 to 7 T.

Magnetoresistance is much larger than classical orbital effects.

Magnetoresistance is nearly independent of magnetic field direction.

Abstract

We report magnetoresistance measurements of hydrogen-terminated (100)-oriented diamond surfaces where hole carriers are accumulated using an ionic-liquid-gated field-effect-transistor technique. Unexpectedly, the observed magnetoresistance is positive within the range of 2<T<10 K and -7<B<7 T, in striking contrast to the negative magnetoresistance previously detected for similar devices with (111)-oriented diamond surfaces. Furthermore we find: 1) magnetoresistance is orders of magnitude larger than that of the classical orbital magnetoresistance; 2) magnetoresistance is nearly independent of the direction of the applied magnetic field; 3) for the in-plane field, the magnetoresistance ratio defined as [rho(B)-rho(0)]/rho(0) follows a universal function of B/T. These results indicate that the spin degree of freedom of hole carriers plays an important role in the surface conductivity of hydrogen-terminated (100) diamond.