Gang Cao Portrait
Professor • PHYS Faculty Mentor (Student's Last Name: A - C)
Physics
Gang.Cao@colorado.edu
(303) 735-4947

Office: DUAN F519

Laboratory: DUAN G223 and G328

Office Hours: Tuesday 3:00 - 5:00 p.m. in DUAN F519 • PHYS-BA Mentoring Form •

Research Interests:

It is widely recognized that whoever controls materials controls technology. 

Our research has focused on the discovery, synthesis, and study of novel quantum materials. It encompasses a methodical search for new quantum materials and a systematic effort to elucidate and control novel quantum states in these materials.  We are particularly interested in strongly correlated materials with strong spin-orbit interactions, such as 4d- and 5d-transition metal oxides. Our studies of these oxides over the last three decades have helped initiate and shape novel lines of research on 4d-electron-based ruthenates and 5d-electron-based iridates. These materials now underpin one of the most important and exciting research areas in contemporary condensed matter physics.  Our laboratory is equipped with advanced techniques for materials synthesis and a large suite of experiemental tools for studies of structural and physical properties, often at extreme conditions, i.e., ultralow temperatures, high magnetic fields and high pressures. We have also established broad collaborations with leading scientists in the US and around the world. 

Visit our Group Website and Google Scholar for more information.

Selected Publications:

  1. Transition between heavy-fermion-strange-metal and spin liquid in a 4d-electron trimer lattice, Hengdi Zhao, Yu Zhang, Pedro Schlottmann, Rahul Nandkishore, Lance DeLong and Gang Cao, Phys. Rev. Lett.; forthcoming 2024.

  2. Current-sensitive Hall effect in a chiral-orbital-current state, Yu Zhang, Yifei Ni, Pedro Schlottmann, Rahul Nandkishore, Lance E. DeLong, and Gang Cao, Nature Communications; forthcoming 2024.   

  3. Evidence for bootstrap percolation dynamics in a photoinduced phase transition, Tyler Carbin, Xinshu Zhang, Adrian B. Culver, Hengdi Zhao, Alfred Zong, Rishi Acharya, Cecilia J. Abbamonte, Rahul Roy, Gang Cao, and Anshul Kogar, Phys. Rev. Lett. 130, 186902 (2023)

  4. Control of chiral orbital currents in a colossal magnetoresistance material, Yu Zhang, Yifei Ni, Hengdi Zhao, Sami Hakani, Feng Ye, Lance DeLong, Itamar Kimchi and Gang Cao, Nature 611, 467–472 (2022)

  5. Emergence of spinons in layered trimer iridate Ba4Ir3O10,Y. Shen, J. Sears, G. Fabbris, A. Weichselbaum, W. Yin, H. Zhao, D. G. Mazzone, H. Miao, M. H. Upton, D. Casa, R. S. Acevedo-Esteves, C. Nelson, A. M. Barbour, C. Mazzoli, G. Cao, and M. P. M. Dean, Phys. Rev. Lett.129, 207201 (2022)

  6. Keldysh space control of charge dynamics in a strongly driven Mott insulator, Xinwei Li, Honglie Ning, Omar Mehio, Hengdi Zhao, Min-Cheol Lee, Kyungwan Kim, Fumihiko Nakamura, Yoshiteru Maeno, Gang Cao, and David Hsieh, Phys. Rev. Lett. 128, 187402 (2022) 

  7. Mechanical control of physical properties in the van der Waals ferromagnet Cr2Ge2Te6 via application of electric current, Hengdi Zhao, Yifei Ni, Bing Hu, Sabastian Selter, Saicharan Aswartham, Yu Zhang, Bernd Buchner, Pedro Schlottmann, and Gang Cao, Phys. Rev. B 106, L041103 (2022)

  8. Magnetic structure and spin fluctuations in the colossal magnetoresistance ferrimagnet Mn3Si2Te6, Feng Ye, Masaaki Matsuda, Zachary Morgan, Todd Sherline,Yifei Ni, Hengdi Zhao ,and G. Cao, Letter of Phys. Rev. B 106, L180402 (2022); Editors' Suggestion

  9. Monograph: Physics of Spin-Orbit-Coupled Oxides,  Gang Cao and Lance E. DeLong, Oxford University Press, ISBN 978-0-19-960202-5; 2021

  10. Colossal magnetoresistance via avoiding fully polarized magnetization in ferrimagnetic insulator Mn3Si2Te6, Yifei Ni, Hengdi Zhao, Yu Zhang, Bing Hu, Itamar Kimchi and Gang Cao, Phys. Rev. B 103, L161105 (2021);Editors' Suggestion

  11. Flexible lattice in Ca3Ru2O7: Control of the electrical transport via anisotropic magnetostriction, Hengdi Zhao, Hao Zheng, Jasminka Terzic, Wenhai Song, Yifei Ni, Yu Zhang, Pedro Schlottmann and Gang Cao, Phys. Rev. B 104, L121119 (2021)

  12. The ground state in a proximity to a possible Kitaev spin liquid: An undistorted honeycomb iridate NaxIrO3 (0.60 < x < 0.80), Hengdi Zhao, Bing Hu, Feng Ye, Minhyea Lee, Pedro Schlottmann and Gang Cao, Letter of Phys. Rev. B 104, L041108 (2021); Editors' Suggestion

  13. Quest for quantum states via field-editing technology, Gang Cao, Hengdi Zhao, Bing Hu, Nicholas Pellatz, Dmitry Reznik, Pedro Schlottmann and Itamar Kimchi, npj Quantum Mater. 5, 83 (2020)

  14. Quantum liquid from strange frustration in the trimer magnet Ba4Ir3O10, G. Cao, H. D. Zhao, H. Zheng, Y. F. Ni, Christopher. A. Pocs, Y. Zhang, Feng, Ye, Christina Hoffmann, Xiaoping Wang, Minhyea Lee, Michael Hermele and Itamar Kimchi, npj Quantum Mater. 5, 26 (2020)

  15. Topical Review: Towards electrical-current control of quantum states in spin-orbit-coupled matter, Gang Cao, Journal of Physics: Condensed Matter 32, 423001 (2020)  

  16. Possible quantum paramagnetism in compressed Sr2IrO4, D. Haskel, G. Fabbris, J. H. Kim, L. S. I. Veiga, J. R. L. Mardegan, C. A. Escanhoela, Jr., S. Chikara, V. Struzhkin, T. Senthil, B. J. Kim, G. Cao, and J.W. Kim, Phys. Rev. Lett. 124, 067201 (2020)

  17. Pseudospin-lattice coupling and electric control of the square-lattice iridate Sr2IrO4, Feng Ye, Christina Hoffmann, Wei Tian, Hao Zheng, Hengdi Zhao, and G. Cao, Phys. Rev. B 102, 115120 (2020)

  18. Persistent insulating state at megabar pressures in strongly spin-orbit-coupled Sr2IrO4, Chunhua Chen, Yonghui Zhou, Xuliang Chen, Tao Han, Chao An, Ying Zhou, Yifang Yuan, Bowen Zhang, Shuyang Wang, Ranran Zhang, Lili Zhang, Changjing Zhang, Zhaorong Yang, Lance E. DeLong and Gang Cao, Phys. Rev. B 101, 144102 (2020)

  19. Direct detection of dimer orbitals in Ba5AlIr2O11, Y. Wang, Ruitang Wang, Jungho Kim, M. H. Upton, D. Casa, T. Gog, G. Cao, J. P. Hill, G. Kotliar,M. P. M. Dean,and X. Liu, Phys. Rev. Lett.,122, 106401 (2019)

  20. Nonequilibrium orbital transitions via applied electrical current in calcium ruthenate, Hengdi Zhao, Bing Hu, Feng Ye, Christina Hoffmann, Itamar Kimchi and Gang Cao; Phys. Rev. B 100, 241104(R) (2019)

  21. Electrical control of structural and physical properties via spin-orbit interactions in Sr2IrO4, G. Cao, J. Terzic, H. D. Zhao, H. Zheng, Peter Riseborough, L. E. DeLong, Phys. Rev. Lett. 120, 017201 (2018); Editors' Suggestion

  22. Observation of a pressure-induced transition from interlayer ferromagnetism to intralayer antiferromagnetism in Sr4Ru3O10, H . Zheng, W.H. Song, J. Terzic, H. D. Zhao, Y. Zhang, Y. F. Ni, L. E. DeLong, P. Schlottmann and G. Cao, Phys. Rev. B 98, 064418 (2018); Editors' Suggestion

  23. The Challenge of spin-orbit-tuned ground states in iridates: A Key Issues Review, Gang Cao and Pedro Schlottmann, Reports on Progress in Physics 81 042502 (2018) 

  24. “Novel magnetism of Ir5+ (5d4) ions in the double perovskite Sr2YIrO6, G. Cao, T. F. Qi, L. Li, J. Terzic, S. J. Yuan, L. E. DeLong, G. Murthy and R. K. Kaul, Phys. Rev. Lett. 112, 056402 (2014)

  25. Lattice-tuned magnetism of Ru4+(4d4) ions in single-crystals of the layered honeycomb ruthenates: Li2RuO3 and Na2RuO3, J. C. Wang, J. Terzic, T. F. Qi, Feng Ye, S. J. Yuan, S. Aswartham, S. V. Streltsov, D. I. Khomskii, R. K. Kaul and G. Cao, Phys. Rev. B 90 161110 (R) (2014)

  26. Monograph: Frontiers of 4d- and 5d-Transition Metal Oxides, Gang Cao and Lance E. De Long, World Scientific, London, 2013; ISBN: 978-981-4374-859

  27. Negative volume thermal expansion via orbital and magnetic orders in single-crystal Ca2Ru1-xCrxO4, T.F. Qi, O.B. Korneta, S. Parkin, L.E. DeLong, P. Schlottmann and G. Cao, Phys. Rev. Lett. 105, 177203 (2010)

  28. Observation of strong spin valve effect in bulk Ca3(Ru1-xCrx)2O7, G. Cao, V. Durairaj S. Chikara L. E. DeLong and P. Schlottmann, Phys. Rev. Lett. 100, 159902 (2008)

  29. Colossal magnetoresistance by avoiding a ferromagnetic state in Mott system Ca3Ru2O7, X. N. Lin, Z.X. Zhou, V. Durairaj, P. Schlottmenn and G. Cao, Phys. Rev. Lett. 95, 017203 (2005)

  30. Anomalous magnetic and transport properties in magnetic insulator Sr3Ir2O7, G. Cao, Y. Xin, C. S. Alexander, J.E. Crow and P. Schlottmann, Phys. Rev. B 66, 214412 (2002)

  31. Charge density wave formation accompanying ferromagnetic ordering in quasi-one-dimensional BaIrO3, G. Cao, J.E. Crow, R.P. Guertin, P. Henning, C.C. Homes, M. Strongin, D.N. Basov, and E. Lochner, Solid State Comm. 113, 657 (2000)

  32. Weak ferromagnetism, metal-to-nonmetal transition and negative differential resistivity in single crystal Sr2IrO4, G. Cao, J. Bolivar, S. McCall, J.E. Crow, and R.P. Guertin, Phys. Rev. B 57, R11039 (1998)

  33. Observation of a metallic antiferroamgnetic phase and metal-nonmetal transition in Ca3Ru2O7, G. Cao, S. McCall, J.E. Crow and R.P. Guertin, Phys. Rev. Lett. 78, 1751 (1997)

  34. Thermal, magnetic and transport properties of single crystal Sr1-xCaxRuO3 (0 < x < 1.0), G. Cao, S. McCall, M. Shepard, J. E. Crow, and R. P. Guertin, Phys. Rev. B 56, 321 (1997)

  35. Magnetic and transport properties of single crystal Ca2RuO4: Relationship to superconducting Sr2RuO4, G. Cao, S. McCall, M. Shepard, J.E. Crow and R.P. Guertin, Phys. Rev. B 56, R2916 (1997)