講演情報
[8a-N304-5]Influence of Fermi energy tuning on anomalous Nernst effect in (Co1-xNix)2MnGa composition spread epitaxial film
〇(D)Benugopal Bairagya1,2,3, G Xing2, Nanhe Kumar Gupta2, Vineet Barwal2, Keisuke Masuda2, Weinan Zhou2, Sanjay Singh3, Yuya Sakuraba2,1 (1.Uni. of Tsukuba, 2.NIMS, 3.IITBHU)
キーワード：
spintronics、thin film、electronic transport
Co2MnGa, a well Known nodal line semimetal with a Heusler L21 structure, exibits both giant anomalous Hall effect (AHE) and a significant anomalous Nernst effect (ANE). However, the theoretically studies predict that maximum positive value of anomalous Nernst conductivity (ANC) appears at an energy slightly above the Fermi level. Therefore tuning the Fermi level via electron doping can be a promising strategy to increase the ANC in Co2MnGa. Substitution of Co with Ni is a suitable approach for electron doping while keeping the L21 ordered structure, as Ni2MnGa is also known to form a well ordered L21 structure. To experimentally explore this, we synthesized a (Co1-xNix)2MnGa composition spread epitaxial thin film and confirmed the L21 structure across the composition spread via XRD . Measurement devices for 21 compositions were fabricated to extract ANC from AHE, ANE, Seebeck, and resistivity data. Contrary to theoretical predictions ANC decreased with Ni doping. Anisotropic magnetoresistance and anomalous XRD confirmed the intended Fermi level shift and Ni substitution at Co sites. We then incorporated an onsite Coulomb interaction (U) at the Co site in the theoretical model, which reconciled the experimental and theoretical ANC for a specific U value. This result highlights the importance of including onsite Coulomb interaction at the Co site to accurately reproduce the the experikmentally observed ANC.