Exploration and quantum tranport study of topological quantum materials

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Our work aims at the search for and characterization of new classes of magnets with noncoplanar ordering, which may have applications in the search for topologically protected electronic surface modes. These are sought after for low-loss electronics and for potential applications in quantum computation.In the hexagonal systems Gd3Ru4Al12 and Gd2PdSi3, we discovered or helped to discover the first examples of skyrmion lattice phases in bulk centrosymmetric magnets. As compared to previous work, these show new phenomenology due to the absence of chiral (left- or right-handed) interactions. In Dy3Ru4Al12, we found a new form of canted antiferromagnet, where magnetic anisotropy and exchange interactions mediated by the conduction electrons induce an unconventional, noncoplanar order based on triads of spins. In all these cases, large transport responses, such as topological Hall and Nernst effects, result from the magnetic ordering and were observed by us. Technical aspects of our work included material search based on symmetry principles, growth of large single crystals using solid state techniques (including solid solutions), characterization of these crystals using x-ray techniques, as well as through bulk thermodynamic and transport measurements.