Abstract:
Progress in condensed-matter physics ultimately depends on materials reality. Many long-standing questions arise not from a lack of theoretical ideas, but from the challenge of controlling defects, disorder, stoichiometry, and strain in real materials. In this talk, I will discuss altermagnetism in RuO2 - a rutile 4d transition-metal oxide - from the perspective of materials synthesis.
Using chemistry-guided, atomically controlled epitaxial growth, we systematically tune strain and materials quality in RuO2 thin films, including films approaching the unit-cell limit while retaining metallicity. This materials control enables us to distinguish intrinsic electronic and magnetic behavior from effects arising from defects, relaxation, and structural inhomogeneity. Combining advanced X-ray scattering and absorption spectroscopy, transmission electron microscopy, temperature-dependent transport, magneto-optical measurements, polarized neutron reflectometry (PNR) and DFT calculations, we find robust strain-induced magnetism in epitaxial RuO2 consistent with an altermagnetic metallic phase.
I will also discuss the emergence of a polar phase in strained RuO2 films and heterostructures, which can strongly modify interfacial electronic structure and transport properties. These results show how synthesis and structural control are essential for resolving emergent quantum phenomena in complex oxides, particularly when their signatures are highly sensitive to subtle variations in material structure and defects.
Host: Divine Kumah
Event Series
DMI Seminar Series