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P7 Iridates and spin liquids

The aim of this project is to search for, and synthesize, solid state materials with topological and spin liquid properties for the benefit of the VI. Of special interest are effective spin-1/2 spin liquids where quantum effects are most pronounced. Although these have been long sought, promising examples have only come along very recently with materials such as the triangular lattice systems κ-(BEDT-TTF)2Cu2(CN)3 and Ba3CuSb2O9, the Kagome system ZnCu3(OH)6Cl2 (Herbertsmithite), and the hyperkagome system Na4Ir3O8. Another important factor in spin liquids can be orbital degeneracy. Orbital degeneracy is common but often removed by Jahn Teller distortion. For a frustrated system, though, this is not necessarily the case and the orbitals can provide another quantum degree of freedom which promotes liquid formation.

People in charge: Dr. Veronika Fritsch, Friedrich Freund

Previous PhD student: Soham Manni



S. Lucas, K. Grube, C.-L. Huang, A. Sakai, S. Wunderlich, E. L. Green, J. Wosnitza, V. Fritsch, P. Gegenwart, O. Stockert, and H. v. Löhneysen, Entropy Evolution in the Magnetic Phases of Partially Frustrated CePdAl, Phys. Rev. Lett. 118, 107204 (2017)


A. Sakai, S. Lucas, P. Gegenwart, O. Stockert, H. v. Löhneysen, V. Fritsch, Signature of frustrated moments in quantum critical CePd1−xNixAl, Phys. Rev. B 94, 220405(R) (2016)

S. C. Williams, R. D. Johnson, F. Freund, Sungkyun Choi, A. Jesche, I. Kimchi, S. Manni, A. Bombardi, P. Manuel, P. Gegenwart, R. Coldea, Incommensurate counterrotating magnetic order stabilized by Kitaev interactions in the layered honeycomb α-Li2IrO3, Phys. Rev. B 93, 195158 (2016), open access version: arXiv:1602.07990


F. Lüpke, S. Manni, S. C. Erwin, I. I. Mazin, P. Gegenwart, and M. Wenderoth; Highly unconventional surface reconstruction of Na2IrO3 with persistent energy gap, Phys. Rev. B 91, 041405(R) (2015), open access version: arXiv: 1407.4697


A. Biffin, R. D. Johnson, Sungkyun Choi, F. Freund, S. Manni, A. Bombardi, P. Manuel, P. Gegenwart, and R. Coldea; Unconventional magnetic order on the hyperhoneycomb Kitaev lattice in β-Li2IrO3: Full solution via magnetic resonant x-ray diffraction, Phys. Rev. B 90, 205116 (2014), open access version: arXiv:1408.0246

Manni, S., Tokiwa, Y., Gegenwart, P.; Effect of nonmagnetic dilution in the honeycomb-lattice iridates Na2IrO3 and Li2IrO3. Phys. Rev. B 89 (2014) 241102(R), open access version:.  arXiv:1404.4253

Manni, S., Choi, S., Mazin, I.I., Coldea, R., Altmeyer, M., Jeschke, H.O., Valenti, R., Gegenwart, P.; Effect of isoelectronic doping on the honeycomb-lattice iridate A2IrO3. Phys. Rev. B 89 (2014) 245113, open access version: arXiv:1312.0815

Y. Tokiwa, J. J. Ishikawa, S. Nakatsuji, P. Gegenwart, Quantum criticality in a metallic spin liquid, Nature Materials 13, (2014) 356, open access version: arXiv:1401.4155


Gretarsson, H., Clancy, J.P., Liu, X., Hill, J.P., Bozin, E., Singh, Y., Manni, S., Gegenwart, P., Kim, J., Said, A.H., Casa, D., Gog, T., Upton, M.H., Kim, H.S., Yu, J., Katukuri, V.M., Hozoi, L., van den Brink, J., Kim, Y.J.; Crystal-Field Splitting and Correlation Effect on the Electronic Structure of A2IrO3. Phys. Rev. Lett. 110 (2013) 076402, open access version: arXiv:1304.4484

Mazin, I. I., Manni, S., Foyevtsova, K., Jeschke, H.O., Gegenwart, P., Valenti, R.; Origin of the insulating state in honeycomb iridates and rhodates. Phys. Rev. B 88 (2013) 035115, open access version: [arxiv:1304.2258]

Singh, Y., Tokiwa, Y., Dong, J., Gegenwart, P.; Spin liquid close to a quantum critical point in Na4Ir3O8, Phys. Rev. B 88 (2013) 220413, open access version: arXiv:1312.3123

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