Spin Hall magnetoresistance studies of differently strained ultrathin SrMnO₃ films

The ability to tune magnetic ordering in a nominally antiferromagnetic insulator, making use of the co-dependence of the charge, spin and orbital degrees of freedom in transition metal oxides, opens a vast playing field in the area of antiferromagnetic spintronics. We use Spin Hall magnetoresistance (SMR) as a probe of the magnetic ordering in thin films of SrMnO₃ (SMO) when grown on two different substrates –SrTiO₃ (STO) and LaAlO₃ (LAO) -that changes the induced strain from tensile to compressive respectively. An in-plane magnetic field dependent angular measurement of the transverse resistivity of Pt Hall bars patterned on SMO films were studied for both cases. The compressively strained SMO film on LAO shows a 180^o phase shift relative to the tensile strained SMO film on STO, suggesting a change in the magnetic ordering from antiferromagnetic to ferromagnetic. This is brought about by the presence of oxygen vacancies promoted by the underlying tensile strain in SMO on STO. This work shows the unique possibility of tailoring the magnetic properties in complex oxides with strain and the ability of interface spin-transport probes as SMR to fingerprint them, establishing their suitability for magnon transport studies.