Spin Hall Magnetoresistance in Spintronic Systems

Spin Hall magnetoresistance (SMR) arises in bilayers and multilayers that combine a non-magnetic metal with strong spin–orbit coupling and an adjacent magnetic insulator or antiferromagnet. When an electric current passes through the metal layer, the spin Hall effect generates a transverse spin current that accumulates at the interface. Reflected spins impart a backflow torque that depends on the orientation of the magnetic order, leading to a modulation of the electrical resistance in the metal. This non-reciprocal resistance variation provides a powerful tool to probe interfacial spin transport, magnetic anisotropy and dynamic spin textures without the need for direct charge transfer into the magnetic layer. Over the past decade, SMR has been applied to diverse material systems—including ferromagnetic insulators, antiferromagnets and diluted magnetic semiconductors—to reveal fundamental aspects of spin mixing conductance, magnetic phase transitions and the influence of interface chemistry and morphology. Beyond fundamental interest, these effects underpin emerging spintronic technologies such as low-power magnetic memory, spin-orbit torque devices and hybrid magnonic circuits, where electrical detection of magnetic states and spin currents is indispensable.

Research from Nature Portfolio

Recent theoretical work has extended the SMR framework to account for unusual anisotropic magnetoresistance in bilayer heterostructures by introducing a two-vector transport formalism. This generalisation captures the angular dependence of both longitudinal and transverse resistivity when the magnetisation rotates in three mutually orthogonal planes, reconciling experiments that deviate from conventional spin Hall magnetoresistance predictions. Foundational experimental studies have also employed SMR probes to characterise antiferromagnetic insulators, extracting anisotropy constants and Dzyaloshinskii–Moriya fields across phase transitions solely from electrical measurements. In another key advance, heterostructures of non-magnetic metals on magnetic insulators were used to demonstrate pure spin Hall magnetoresistance free of magnetic proximity effects. Comparative measurements in platinum and rhodium on yttrium iron garnet revealed that the non-magnetised metal maintains a pure spin current, establishing an ideal platform for investigating interfacial spin mixing conductance and spin-orbit torque phenomena.

Spin Hall Magnetoresistance in Spintronic Systems publication trend

The graph below shows the total number of articles in spin hall magnetoresistance in spintronic systems across all publications each year (not limited to Nature Index journals).

Technical terms

Spin Hall effect: Conversion of a charge current into a transverse spin current in materials with strong spin–orbit coupling.

Spin Hall magnetoresistance (SMR): Variation of electrical resistance in a non-magnetic metal due to spin current reflection at an adjacent magnetic layer.

Spin mixing conductance: Quantitative measure of the efficiency of spin current transfer across an interface between a metal and a magnetic material.

Néel vector: Order parameter describing the relative orientation of sublattice magnetisation in an antiferromagnet.

Magnetic anisotropy: Dependence of magnetic energy on the direction of magnetisation within a crystal or thin film.

References

1. A theory of unusual anisotropic magnetoresistance in bilayer heterostructures. Scientific Reports (2023).
2. Anisotropies and magnetic phase transitions in insulating antiferromagnets determined by a Spin-Hall magnetoresistance probe. Communications Physics (2019).
3. Pure spin-Hall magnetoresistance in Rh/Y3Fe5O12 hybrid. Scientific Reports (2015).
4. Interface morphology effect on the spin mixing conductance of Pt/Fe3O4 bilayers. Scientific Reports (2018).
5. Effect of interface quality on spin Hall magnetoresistance in Pt/MgFe2O4 bilayers. Applied Physics Express (2023).
6. Detection of antiferromagnetic order in a RuO2/Pt bilayer by spin Hall magnetoresistance. AIP Advances (2024).
7. Spin Hall magnetoresistance in Pt/(Ga,Mn)N devices. Applied Physics Letters (2024).