Low temperature physics

Superfluidity and superconductivity.

  • Dmytro Lotnyk, Anna Eyal, Nikolay Zhelev, Abhilash Sebastian, Yefan Tian, Aldo Chavez, Eric Smith, John Saunders, Erich Mueller and Jeevak Parpia, "Path-dependent supercooling of the 3He superfluid A-B transition", Phys. Rev. Lett. 126, 215301 (2021).

NMR investigations on topological quantum materials

There are different types of topological materials have been studied in this project, including topological nodal-line semimetal ZrSi(Te, Se, S), topological semimetal ZrTe2 and topological insulator/semimetal ZrTe5.

  • Yefan Tian, Yanglin Zhu, Rui Li, Zhiqiang Mao, and Joseph H. Ross, Jr., “NMR study of nodal-line semimetal ZrSiSe”, In preparation.

  • Yefan Tian, Yanglin Zhu, Rui Li, Zhiqiang Mao, and Joseph H. Ross, Jr., “NMR determination of Van Hove singularity and Lifshitz transitions in nodal-line semimetal ZrSiTe”, Phys. Rev. B 104, L041105 (2021).

  • Yefan Tian, Nader Ghassemi, and Joseph H. Ross, Jr., “Gap-opening transition in Dirac semimetal ZrTe5”, Phys. Rev. Lett. 126, 236401 (2021).

  • Yefan Tian, Nader Ghassemi, and Joseph H. Ross, Jr., “Topological nodal line in ZrTe2 demonstrated by nuclear magnetic resonance”, Phys. Rev. B 102, 165149 (2020).

  • Yefan Tian, Nader Ghassemi, and Joseph H. Ross, Jr., “Dirac electron behavior and NMR evidence for topological band inversion in ZrTe5”, Phys. Rev. B 100, 165149 (2019).

NMR investigations on advanced thermoelectric materials

Several different types of thermoelectric materials have been studied, including half-Heuslers and skutterudites. Half-Heusler, or semi-Heusler, compounds (space group F43m) comprise a relatively large family of materials with diverse physical properties and applications. Functional materials based on these compounds include thermoelectric semiconductors, piezoelectric semiconductors, optoelectronic semiconductors, and topological insulators.

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Half-Heusler

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Skutterudite

  • Yefan Tian, Yuqi Chen, Ali A. Sirusi, Nader Ghassemi, Sekine Chihiro, and Joseph H. Ross, Jr., “NMR study of doped skutterudites YbxCo4Sb12”, In preparation.

  • Nader Ghassemi, Yefan Tian, Xu Lu, Yanci Yan, Xiaoyuan Zhou, and Joseph H. Ross, Jr., “Rattling and band-filling effects in substituted tetrahedrites: an NMR study”, Submitted to Adv. Funct. Mater. (2021).

  • Yefan Tian, Farit G. Vagizov, Nader Ghassemi, Wuyang Ren, Hangtian Zhu, Zhiming Wang, Zhifeng Ren, and Joseph H. Ross, Jr., “Defect charging and resonant levels in half-Heusler Nb1−xTixFeSb”, Mater. Today Phys. 16, 100278 (2021).

  • Yefan Tian, Nader Ghassemi, Wuyang Ren, Hangtian Zhu, Shan Li, Qian Zhang, Zhiming Wang, Zhifeng Ren, and Joseph H. Ross, Jr., “Half-Heusler thermoelectric materials: NMR studies”, J. Appl. Phys. 128, 055106 (2020).

  • Nader Ghassemi, Yefan Tian, Xu Lu, Yanci Yan, Xiaoyuan Zhou, and Joseph H. Ross, Jr., “Copper ion dynamics and phase segregation in Cu-rich tetrahedrite: an NMR study”, J. Phys. Chem C. 124, 3973 (2020).

  • Yefan Tian, Ali A. Sirusi, Sedat Ballikaya, Nader Ghassemi, Ctirad Uher, and Joseph H. Ross, Jr., “Charge-carrier behavior in Ba-, Sr- and Yb-filled CoSb3: NMR and transport studies”, Phys. Rev. B 99, 125109 (2019).

  • Nader Ghassemi, Xu Lu, Yefan Tian, Emily Conant, Yanci Yan, Xiaoyuan Zhou, and Joseph H. Ross, Jr., “Structure change and rattling dynamics in Cu12Sb4S13 tetrahedrite: an NMR study”, ACS Appl. Mater. Interfaces 10, 36010 (2018).

  • Yefan Tian, Hangtian Zhu, Wuyang Ren, Nader Ghassemi, Emily Conant, Zhiming Wang, Zhifeng Ren, and Joseph H. Ross, Jr., “Native defects and impurity band behavior in half-Heusler thermoelectric NbFeSb”, Phys. Chem. Chem. Phys. 20, 21960 (2018).

Machine learning approach to FINEMET-type soft magnetic alloys design

This work focuses on new soft magnetic materials design. We take advantage of materials informatics to build statistical model which is able to link processing procedures and materials properties together. Fe-based nanocrystalline alloys is main type of material to be studied. Data set is extracted from experimental results of publications.

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B-H loop

  • Yuhao Wang*, Yefan Tian*, Tanner Kirk, Omar Laris, Joseph H. Ross, Jr., Ronald D. Noebe, Vladimir Keylin, and Raymundo Arroyave, “Accelerated design of Fe-based soft magnetic materials using machine learning and stochastic optimization”, Acta Mater. 194, 144 (2020). (*equal contribution)