Spin-Orbit Coupling and Topological Systems

 

Phase transitions in condensed matter physics generally have been identified with an order parameter that spontaneously breaks the symmetry of the system and develops long range order, such as for the magnetization that develops in a ferromagnet below the Curie temperature or the staggered magnetization below the Néel temperature in an antiferromagnet.   With the discovery of the Integer Quantum Hall Effect, and now for Topological Insulators (TI), the traditional classification of quantum phases of matter has expanded.  These latter systems lack the concept of spontaneous symmetry breaking, rather exhibiting topological order associated with the presence of nontrivial topological components that lead to gapless boundary modes with chirality. One of the essential properties of TI's is a strong spin-orbit interaction, which interaction becomes larger the heavier the element.  For the well-studied 3d systems the spin-order interaction typically does not play an essential role, which is one of the reasons attention in the condensed matter community has turned to 4d, 5d, and 5f systems. 

Half-Heusler Topological Insulators

In the so-called Z2 two-dimensional and three-dimensional systems, these topologically protected metallic states are of interest not only from a fundamental point of view, but also because they have the technological potential to transform spintronics and quantum computation applications. Even more interesting are systems that exhibit both symmetry breaking order parameters and topologically nontrivial states, which can give rise to exotic collective modes and states.  One such family is represented by the cubic half-Heusler materials on which we have been collaborating.  The antiferromagnetism breaks time reversal and translational symmetries but preserves the combination, leading to a new type of system, the antiferromagnetic topological insulator.

Topological RPdBi half-Heusler semimetals:  a new family of non-centrosymmetric magnetic superconductors, Y. Nakajima, R. Hu, K. Kirshenbaum, A. Hughes, P. Syers, X. Wang, K. Wang, R. Wang, S. Saha, D. Pratt, J.W. Lynn, and J. Paglione, Science Advances 1, e1500242 (2015).

Large Anomalous Hall Effect in a Half Heusler Antiferromagnet, T. Suzuki, R. Chisnell, A. Devarakonda, Y.-T. Liu, J. W. Lynn, and J. G. Checkelsky, Nature Physics 12, 1119 (2016).

 

5d sytems;  Iridates

Influence of Electron-doping on the Ground State of (Sr1-xLax)2IrO4, Xiang Chen, Tom Hogan, D. Walkup, Wenwen Zhou, M. Pokharel, Mengliang Yao, Wei Tian, Thomas Z. Ward, Y. Zhao, D. Parshall, C. Opeil, J. W. Lynn, Vidya Madhavan, and Stephen D. Wilson, Phys. Rev. B 92, 017125 (2015).

Carrier Localization and Electronic Phase Separation in a doped Spin-Orbit Driven Mott Phase in Sr3(Ir1-xRux)2O7, Chetan Dhital, Tom Hogan, Wenwen Zhou, Xiang Chen, Zhensong Ren, Mani Pokharel, Yoshinori Okada, M. Heine, Wei Tian, Z. Yamani, C. Opeil, J. S. Helton, J. W. Lynn, Ziqiang Wang, Vidya Madhavan, and Stephen D. Wilson, Nature Communications 5, 3377 (2014).

Cd-doping effects in Ce2MIn8 (M=Rh and Ir) Heavy Fermion Compounds, C. Adriano, C. Giles, E. M. Bitter, L. N. Coelho, F. de Bergevin, C. Mazzoll, L. Paolasini, W. Ratcliff, R. Bindel, J. W. Lynn, Z. Fisk, and P. G. Pagliuso, Phys. Rev. B 81, 245115 (2010).

Novel Coexistence of Superconductivity with Two Distinct Magnetic Orders in Heavy Fermion Ce(Rh,Ir)In5, A. D. Christianson, A. Llobet, W. Bao, J. S. Gardner, I. P. Swainson, J. W. Lynn, J.-M. Mignot, K. Prokes, P. G. Pagliuso, N. O. Moreno, J. L. Sarrao, and A. H. Lacerda, Phys. Rev. Lett. 95, 217002 (2005).

Covalency Effects in the Magnetic Form Factor of Ir in K2IrCl6, J. W. Lynn, G. Shirane, and M. Blume, Phys. Rev. Lett. 37, 154 (1976).

4d materials;  Ruthenates

Spin Dynamics and Two-dimensional Correlations in an FCC Antiferromagnetic Sr2YRuO6, S. M. Disseler, J. W. Lynn, R. F. Jardim, M. S. Torikachvili, and E. Granado, Phys. Rev. B 93, 140407(R) (2016).

Two-Dimensional Magnetic Correlations and Partial Long-Range Order in Geometrically Frustrated Sr2YRuO6, E. Granado, J. W. Lynn, R. F. Jardim, and M. Torikachvili, Phys. Rev. Lett. 110, 017202 (2013).

Spin-valve Effect and Magnetoresistivity in Single Crystalline Ca3Ru2O7, W. Bao, Z. Q. Mao, Z. Qu, and J. W. Lynn, Phys. Rev. Lett. 100, 247203 (2008).

Unusual heavy-mass nearly ferromagnetic state with a surprisingly large Wilson ratio in double layered ruthenates (Sr1-xCax)3Ru2O7, Z. Qu, L. Spinu, H. Q. Yuan, V. Dobrosavljeviuc, W. Bao, J. W. Lynn, M. Nicklas, J. Peng, T. J. Liu, D. Fobes, E. Flesch, and Z. Q. Mao, Phys. Rev. B 78, 180407(R) (2008).

Structure and Magnetism of Single Crystal Sr4Ru3O10:  A Ferromagnetic Triple-Layer Ruthenate, M. K. Crawford, R. L. Harlow, W. Marshall, Z. Li, G. Cao, R. L. Lindstrom, Q. Huang, and J. W. Lynn, Phys. Rev. B 65, 214412 (2002).

Synthesis and crystal structure of La3RuO7, P. Khalifah, Q. Huang, J. W. Lynn, R. W. Erwin, and R. J. Cava, Materials Research Bulletin 35, 1 (2000).

Oxygen Displacements and Search for Magnetic Order in Sr3Ru2O7, Q. Huang, J. W. Lynn, R. W. Erwin, J. Jarupatrakorn, and R. J. Cava, Phys. Rev. B 58, 8515 (1998).

5f materials;  Hidden order in URu2Si2

Distinct magnetic spectra in the hidden order and antiferromagnetic phases in URu2-xFexSi2, Nicholas P. Butch, Sheng Ran, Inho Jeon, Noravee Kanchanavatee, Kevin Huang, Alexander Breindel, M. Brian Maple, Ryan L. Stillwell, Yang Zhao, Leland Harriger, and Jeffrey W. Lynn, (submitted).

Chemical Pressure Tuning of URu2Si2 via Isoelectronic Substitution of Ru with Fe, Pinaki Das, N. Kanchanavatee, J. S. Helton, K. Huang, R. E. Baumbach, E. D. Bauer, B. D. White, V. W. Burnett, M. B. Maple, J.W. Lynn, and M. Janoschek, Phys. Rev. B 91, 085122 (2015).

Symmetry and Correlations Underlying Hidden Order in URu2Si2, Nicholas P. Butch, Michael E. Manley, Jason R. Jeffries, Marc Janoschek, Kevin Huang, M. Brian Maple, Ayman H. Said, Bogdan M. Leu, and Jeffrey W. Lynn, Phys. Rev. B 91, 035128 (2015).

Absence of a static in-plane magnetic moment in the "hidden-order" phase of URu2Si2, P. Das, R. E. Baumbach, E. D. Bauer, K. Huang, M. B. Maple, Y. Zhao, J. Helton, J. W. Lynn, and M. Janoschek, New J. Phys. 15, 053031(2013).

Antiferromagnetic Critical Pressure in URu2Si2 under Hydrostatic Conditions, N. P. Butch, J. R. Jeffries, S. X. Chi, J. B. Leão, and J. W. Lynn, and M. B. Maple, Phys. Rev. B 82, 060408(R) (2010)

Non-Fermi Liquid Behavior and Quantum Criticality in Sc1-xUxPd3 and URu2-xRexSi2, M. B. Maple, N. P. Butch, E. D. Bauer, V. S. Zapf, P.-C. Ho, S. D. Wilson , P. Dai, D. T. Adroja, S.-H. Lee, J.-H. Chung, J. W. Lynn, Physica B  378-380, 911 (2006).

 

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