Magnetoresistance Measurements as an Alternative to Magnetic Resonance Methods for Studying Paramagnetic Defects

Magnetic resonance methods such as electronic paramagnetic resonance and other companion methods like electrically detected magnetic resonance have been popular for studying unpaired spins in a wide array of materials. In some situations resonance methods are not feasible — for instance when a system of interest is beneath conductive layers as in three-dimensional integrated circuits.

Recently an alternative approach to probing paramagnetic spins was devised which does not require any electromagnetic resonant field but instead magnetoresistance is measured near zero field [1]. The magnetoresistance arises from correlations between spin pairs that involve either a carrier recombining at a trap or hopping through a trap [2]. This magnetoresistance method can be used in electronic devices to great advantage by probing paramagnetic defect environments such as hyperfine and spin-orbit couplings. A theoretical description of the magnetoresistance effect utilizes a multi-spin stochastic Liouville equation [3] which provides agreement with recombination currents in MOSFETs. For high-nuclear spin defects, the theory predicts new resonances in the magnetoresistance that provide precise determination of hyperfine constants. These results offer a new means of analysis which does not rely on a resonator and are potentially applicable to systems inaccessible to conventional resonance methods.

This work was done in collaboration with the groups of M. E. Flatté (U of Iowa ) and P. A. Lenahan (Penn. State U).

[1] J. Ashton et al, IEEE Trans. on Nucl. Sci. 66, 428 (2019)
[2] J. Rybicki et al, Phys. Rev. Lett. 109, 076603 (2012)
[3] Y. Wang et al, Phys. Rev. X 6, 011011 (2016)