研究领域

Materials chemistry/synthesis of new oxide/intermetallic/pnictide and chalcogenide compounds and characterization of their crystal structures and electronic and magnetic properties. Joint appointment with Princeton Institute for the Science and Technology of Materials (PRISM).

In our research group, we search for and synthesize non-molecular solids with the goal of finding new materials with exotic electronic and magnetic properties. We find new compounds, grow crystals from the melt and vapor transport, determine their crystal structures, and characterize their electronic and magnetic properties. The choice of chemical systems to be studied is informed by understanding how chemistry and structure combine to yield the electronic properties of solids; understanding what the important forefront areas of research are in condensed matter physics is always an important part of the equation. When a new compound appears to be particularly interesting, we work closely with colleagues in theoretical and experimental condensed matter physics at Princeton, Johns Hopkins and Penn State Universities, Brookhaven, and many other laboratories around the world to study the properties in detail and alter them through chemical and structural manipulation. We work closely with experts in high resolution electron microscopy to determine the crystal structures of complex materials and learn about their nanometer scale structure. We perform temperature dependent neutron diffraction measurements with collaborators at the National Institute of Standards and Technology and the Spallation Neutron Source at Oak Ridge National Laboratory, and synchrotron x-ray diffraction at Brookhaven and Argonne National Laboratories to determine the crystal and magnetic structures of the new materials we make. The detailed structural information obtained in these experiments is correlated with the measured physical properties of the materials. Elementary electronic structure calculations are performed to help direct our exploratory research program and to interpret the properties we observe. Students and postdoctoral fellows are trained in the connections between structure, bonding, and electronic and magnetic properties of non-molecular solids. A major part of our research is in exploring the properties and structures of ternary and quaternary 4d and 5d transition metal oxides – materials that fall at the border between magnetic and non-magnetic low temperature electronic states. Such materials often display unexpected electronic properties. Other major areas of research are new superconductors, new thermoelectrics, and new geometrically frustrated magnets. With a group of researchers in Princeton’s MRSEC program we have played a significant role in the recent discovery and characterization of a new kind of electronic state of matter - topological metallic surface states on the surfaces of certain bulk insulating crystals with strong spin-orbit coupling, known as topological insulators. In all our work, we employ the principles and synthetic and analytical methods of solid state chemistry to find new materials with exceptional physical properties in the hope of driving the study of the electronic properties of solids in new directions through new materials.

近期论文

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“Large, non-saturating magnetoresistance in WTe2”, M.N. Ali, J. Xiong, S. Flynn, J. Tao, Q.D. Gibson, L.M. Schoop, T. Liang, N. Haldolaarachchige, M. Hirschberger, N.P. Ong, and RJ Cava, Nature 514 205 (2014). “Crystal structure and electronic structure of CePt2In7”, T. Klimczuk. O. Walter, L. Muechler, J.W. Krizan, F. Kinnart and R.J. Cava, Journal of Physics, Condensed Matter 26 402201 (2014). “Lattice distortion and stripelike antiferromagnetic order in Ca10(Pt3As8)(Fe2As2)5”, A. Sapkota, G.S. Tucker, M. Ramazanoglu, W. Tian, N. Ni, R.J. Cava, R.J. McQueeney, A.I. Goldman, and A. Kreyssig, Phys. Rev. B90 100504 (2014). “One-dimensional topological edge states of bismuth bilayers”, I.K. Drozdov, A. Alexandradinata, S. Jeon, S. Nadj-Perge, H.W. Ji, R.J. Cava, B.A. Bernevig, and A. Yazdani, Nature Physics 10 664 (2014). “Landau quantization and quasiparticle interference in the three-dimensional Dirac semimetal Cd3As2”, S. Jeon, B.B. Zhou, A. Gyenis, B.E. Feldman, I. Kimchi, A.C. Potter, Q.D. Gibson, R.J. Cava, A. Vishwanath, A. Yazdani, Nature Materials 13 851 (2014). “Large anomalous Hall effect in ferromagnetic insulator-topological insulator heterostructures”, L.D. Alegria, H. Ji, N. Yao, J.J. Clarke, R.J. Cava, and J.R. Petta, Appl. Phys. Lett. 105 53512 (2014). “Experimental Realization of a Three-Dimensional Dirac Semimetal”, S. Borisenko, Q. Gibson, D. Evtushinsky, V. Zabolotnyy, B. Buechner, and R.J. Cava, Phys. Rev. Lett. 113 027603 (2014). “Evidence for SrHo2O4 and SrDy2O4 as model J(1)-J(2) zigzag chain materials” , A. Fennell, V.Y. Pomjakushin, A. Uldry, B. Delley, B. Prevost, A. Desilets-Benoit, A.D. Bianchi, R.I. Bewley, B.R. Hansen, T. Klimczuk, R.J. Cava, and M. Kenzelmann, Phys. Rev. B 89 224511 (2014). “Observation of Distinct Bulk and Surface Chemical Environments in a Topological Insulator under Magnetic Doping”, I. Vobornik, G. Panaccione, J. Fujii, Z.H. Zhu, F. Offi, B.R. Salles, F. Borgatti, P. Torelli, J.P. Rueff, D. Ceolin, A. Artioli, M. Unnikrishnan, G. Levy, M. Marangolo, M. Eddrief, D. Krizmancic, H.W. Ji, A. Damascelli, G. van der Laan, R.G. Egdell, and R.J. Cava, J. Phys. Chem. C 118 12333 (2014). “Visualizing the charge density wave transition in 2H-NbSe2 in real space”, C.J. Arguello, S.P. Chockalingam, E..P Rosenthal, L. Zhao, C. Gutierrez, J.H. Kang, W.C. Chung, R.M. Fernandes, S. Jia, A.J. Millis, R.J. Cava, and A.N. Pasupathy, Phys. Rev. B 89 235115 (2014). “Superconductivity and correlated Fermi liquid behavior in noncentrosymmetric Ca3Ir4Ge4”, F. von Rohr, H.X. Luo, N. Ni, M. Woerle, and RJ Cava, Phys. Rev. B 89 224504 (2014). “NaCaCo2F7: A single-crystal high-temperature pyrochlore antiferromagnet”, J.W. Krizan and R.J. Cava, Phys. Rev. B 89 214401 (2014). “Neutron spectroscopic study of crystal field excitations in Tb2Ti2O7 and Tb2Sn2O7”, J. Zhang, K. Fritsch, Z. Hao, B.V. Bagheri, M.J.P. Gingras, G.E. Granroth, P. Jiramongkolchai, R.J. Cava, and B.D. Gaulin, Phys. Rev. B 89 134410 (2014). “Ferromagnetism in Mn-doped Sb2Te”, H. Luo, Q. Gibson, J. Krizan, and R.J. Cava, J. Phys. Cond. Matt. 26 206002 (2014). “Quasi One Dimensional Dirac Electrons on the Surface of Ru2Sn3” Q.D. Gibson, D. Evtushinsky, A.N. Yaresko, V.B. Zabolotnyy, M.N. Ali, M.K. Fuccillo, J. Van den Brink, B. Buechner, R.J. Cava, and S.V. Borisenko, Scientific Reports 4 5168 (2014). “Superconducting properties and electronic structure of NaBi”, S.K. Kushwaha, J.W. Krizan, J. Xiong, T. Klimczuk, Q.D. Gibson, T. Liang, N.P. Ong, and R.J. Cava, J. Phys. Cond. Matt. 26 212201 (2014). “The Crystal and Electronic Structures of Cd3As2, the Three-Dimensional Electronic Analogue of Graphene”, M.N. Ali, Q. Gibson, S. Jeon, B.B. Zhou, A. Yazdani, and R.J. Cava, Inorg. Chem. 53 4062 (2014). “Magnetic-field-induced shift of the optical band gap in Ni3V2O8”, P. Chen, B.S. Holinsworth, K.R. O’Neal, T.V. Brinzari, D. Mazumdar, Y.Q. Wang, S. McGill, R.J. Cava, B. Lorenz, and J.L. Musfeldt, Phys. Rev. B 89 165120 (2014). “Comparison of Sn-doped and nonstoichiometric vertical-Bridgman-grown crystals of the topological insulator Bi2Te2Se”, SK Kushwaha, Q.D. Gibson, J. Xiong, I. Pletikosic, A.P. Weber, A.V. Fedorov, N.P. Ong, , T. Valla, , R.J. Cava, J. Appl. Phys. 115 143708 (2014). “Hierarchy of Bound States in the One-Dimensional Ferromagnetic Ising Chain CoNb2O6 Investigated by High-Resolution Time-Domain Terahertz Spectroscopy”, C.M. Morris, R.V. Aguilar, A. Ghosh, , S.M. Koohpayeh, J. Krizan, R.J. Cava, O.Tchernyshyov, T.M. McQueen, and N.P. Armitage, Phys. Rev. Lett. 112 137403 (2014).