- Access by Xinjiang University
Compass models: Theory and physical motivations
Rev. Mod. Phys. 87, 1 – Published 12 January, 2015
DOI: https://doi.org/10.1103/RevModPhys.87.1
Abstract
Compass models are theories of matter in which the couplings between the internal spin (or other relevant field) components are inherently spatially (typically, direction) dependent. A simple illustrative example is furnished by the 90° compass model on a square lattice in which only couplings of the form (where denote Pauli operators at site ) are associated with nearest-neighbor sites and separated along the axis of the lattice while couplings appear for sites separated by a lattice constant along the axis. Similar compass-type interactions can appear in diverse physical systems. For instance, compass models describe Mott insulators with orbital degrees of freedom where interactions sensitively depend on the spatial orientation of the orbitals involved as well as the low-energy effective theories of frustrated quantum magnets, and a host of other systems such as vacancy centers, and cold atomic gases. The fundamental interdependence between internal (spin, orbital, or other) and external (i.e., spatial) degrees of freedom which underlies compass models generally leads to very rich behaviors, including the frustration of (semi-)classical ordered states on nonfrustrated lattices, and to enhanced quantum effects, prompting, in certain cases, the appearance of zero-temperature quantum spin liquids. As a consequence of these frustrations, new types of symmetries and their associated degeneracies may appear. These intermediate symmetries lie midway between the extremes of global symmetries and local gauge symmetries and lead to effective dimensional reductions. In this article, compass models are reviewed in a unified manner, paying close attention to exact consequences of these symmetries and to thermal and quantum fluctuations that stabilize orders via order-out-of-disorder effects. This is complemented by a survey of numerical results. In addition to reviewing past works, a number of other models are introduced and new results established. In particular, a general link between flat bands and symmetries is detailed.
Article Text
References (238)
- Anderlini, M., P. J. Lee, B. L. Brown, J. Sebby-Strabley, W. D. Phillips, and J. V. Porto, 2007, Nature (London) 448, 452.
- Andersen, O., and L. Boeri, 2011, Ann. Phys. (Berlin) 523, 8.
- Anderson, P. W., 1959, Phys. Rev. 115, 2.
- Ballhausen, C., 1962, Introduction to Ligand Field Theory (McGraw-Hill, New York).
- Batista, C., and S. Trugman, 2004, Phys. Rev. Lett. 93, 217202.
- Batista, C. D., and Z. Nussinov, 2005, Phys. Rev. B 72, 045137.
- Berlin, T. H., and M. Kac, 1952, Phys. Rev. 86, 821.
- Biskup, M., L. Chayes, and Z. Nussinov, 2005, Commun. Math. Phys. 255, 253.
- Biskup, M., L. Chayes, and S. Starr, 2007, Commun. Math. Phys. 269, 611.
- Biskup, M., and R. Kotecky, 2010, J. Stat. Mech. P11001.
- Bloch, I., J. Dalibard, and W. Zwerger, 2008, Rev. Mod. Phys. 80, 885.
- Breed, D., K. Gilijamse, J. Sterkenburg, and A. Miedema, 1970, J. Appl. Phys. 41, 1267.
- Bricmont, J., and J. Frolich, 1983, Phys. Lett. 122B, 73.
- Browaeys, A., H. Häffner, C. McKenzie, S. L. Rolston, K. Helmerson, and W. D. Phillips, 2005, Phys. Rev. A 72, 053605.
- Bryngelson, J. D., J. N. Onuchic, N. D. Socci, and P. G. Wolynes, 1995, Proteins 21, 167.
- Brzezicki, W., J. Dziarmaga, and A. M. Oleś, 2007, Phys. Rev. B 75, 134415.
- Brzezicki, W., and A. M. Oleś, 2008, Eur. Phys. J. B 66, 361.
- Brzezicki, W., and A. M. Oleś, 2009, Phys. Rev. B 80, 014405.
- Brzezicki, W., and A. M. Oleś, 2010, Phys. Rev. B 82, 060401.
- Brzezicki, W., and A. M. Oleś, 2013, Phys. Rev. B 87, 214421.
- Budnik, R., and A. Auerbach, 2004, Phys. Rev. Lett. 93, 187205.
- Capponi, S., A. Laeuchli, and M. Mambrini, 2004, Phys. Rev. B 70, 104424.
- Casimir, H. B. G., 1948, Proc. K. Ned. Akad. Wet. B51, 793.
- Casimir, H. B. G., and D. Polder, 1948, Phys. Rev. 73, 360.
- Castelnovo, C., R. Moessner, and S. L. Sondhi, 2008, Nature (London) 451, 42.
- Chakrabarty, S., and Z. Nussinov, 2011, Phys. Rev. B 84, 064124.
- Chaloupka, J., G. Jackeli, and G. Khaliullin, 2010, Phys. Rev. Lett. 105, 027204.
- Chang, L.-J., S. Onoda, Y. Su, Y.-J. Kao, K.-D. Tsuei, Y. Yukio, K. Kakurai, and M. R. Lees, 2012, Nat. Commun. 3, 992.
- Chen, G., L. Balents, and A. P. Schnyder, 2009, Phys. Rev. Lett. 102, 096406.
- Chen, H.-D., C. Fang, J. Hu, and H. Yao, 2007, Phys. Rev. B 75, 144401.
- Chen, H.-D., and Z. Nussinov, 2008, J. Phys. A 41, 075001.
- Chern, G. W., N. Perkins, and Z. Hao, 2010, Phys. Rev. B 81, 125127.
- Chern, G.-W., and C. Wu, 2011, Phys. Rev. E 84, 061127.
- Chubokov, A. V., and D. I. Golosov, 1991, J. Phys. Condens. Matter 3, 69.
- Chubukov, A., 1992, Phys. Rev. Lett. 69, 832.
- Cincio, L., J. Dziarmaga, and A. M. Oleś, 2010, Phys. Rev. B 82, 104416.
- Cobanera, E., G. Ortiz, and Z. Nussinov, 2010, Phys. Rev. Lett. 104, 020402.
- Cobanera, E., G. Ortiz, and Z. Nussinov, 2011, Adv. Phys. 60, 679.
- Cobanera, E., G. Ortiz, and Z. Nussinov, 2013, Phys. Rev. B 87, 041105(R).
- Cvetkovic, V., and Z. Tesanovic, 2009, Europhys. Lett. 85, 37002.
- Daghofer, M., K. Wohlfeld, A. M. Oleś, E. Arrigoni, and P. Horsch, 2008, Phys. Rev. Lett. 100, 066403.
- Dagotto, E., 2005, New J. Phys. 7, 67.
- Dagotto, E., T. Hotta, and A. Moreo, 2001, Phys. Rep. 344, 1.
- Divakarian, U., and A. Dutta, 2009, Phys. Rev. B 79, 224408.
- Dorier, J., F. Becca, and F. Mila, 2005, Phys. Rev. B 72, 024448.
- Doucot, B., M. Feigel’man, L. Ioffe, and A. Ioselevich, 2005, Phys. Rev. B 71, 024505.
- Duan, L., E. Demler, and M. Lukin, 2003, Phys. Rev. Lett. 91, 090402.
- Ederer, C., C. Lin, and A. J. Millis, 2007, Phys. Rev. B 76, 155105.
- Elitzur, S., 1975, Phys. Rev. D 12, 3978.
- Emery, V. J., E. Fradkin, S. A. Kivelson, and T. C. Lubensky, 2000, Phys. Rev. Lett. 85, 2160.
- Eriksson, E., and H. Johannesson, 2009, Phys. Rev. B 79, 224424.
- Fazekas, P., 1999, Lecture Notes on Electron Correlation and Magnetism (World Scientific, Singapore).
- Feiner, L. F., and A. M. Oleś, 1999, Phys. Rev. B 59, 3295.
- Feiner, L. F., A. M. Oleś, and J. Zaanen, 1997, Phys. Rev. Lett. 78, 2799.
- Feng, X.-Y., G.-M. Zhang, and T. Xiang, 2007, Phys. Rev. Lett. 98, 087204.
- Ferrero, M., F. Becca, and F. Mila, 2003, Phys. Rev. B 68, 214431.
- Fradkin, E., 1991, Field Theories of Condensed Matter Systems (Addison-Wesley, Redwood City).
- Fradkin, E., and S. A. Kivelson, 1999, Phys. Rev. B 59, 8065.
- Fradkin, E., and S. H. Shenker, 1979, Phys. Rev. D 19, 3682.
- Frank, F. C., and J. S. Kasper, 1958, Acta Crystallogr. 11, 184.
- Frank, F. C., and J. S. Kasper, 1959, Acta Crystallogr. 12, 483.
- Fredenhagen, K., and M. Marcu, 1986, Phys. Rev. Lett. 56, 223.
- Fulde, P., K. Penc, and N. Shannon, 2002, Ann. Phys. (Berlin) 11, 892.
- Golubovic, L., and M. Golubovic, 1998, Phys. Rev. Lett. 80, 4341.
- Goodenough, J., 1963, Magnetism and the Chemical Bond (Interscience, New York).
- Gregor, K., D. A. Huse, R. Moessner, and S. L. Sondhi, 2011, New J. Phys. 13, 025009.
- Greiner, M., M. O. Mandel, T. Esslinger, T. Hansch, and I. Bloch, 2002, Nature (London) 415, 39.
- Griffith, J., 1971, The Theory of Transition Metal Ions (Cambridge University Press, Cambridge, England).
- Harris, A., T. Yildirim, A. Aharony, O. Entin-Wohlman, and I. Korenblit, 2003, Phys. Rev. Lett. 91, 087206.
- Harrison, W., 2004, Elementary Electronic Structure (World Scientific, Singapore), revised edition.
- Hastings, M. B., 2004, Phys. Rev. B 69, 104431.
- Henley, C., 1989, Phys. Rev. Lett. 62, 2056.
- Henley, C. L., 2005, Phys. Rev. B 71, 014424.
- Honecker, A., D. Cabra, H.-U. Everts, P. Pujol, and F. Stauffer, 2007, J. Phys. Condens. Matter 19, 145249.
- Horibe, Y., M. Shingu, K. Kurushima, H. Ishibashi, N. N. Ikeda, K. Kato, Y. N. Motome, Furukawa, Mori, and T. Katsufuji, 2006, Phys. Rev. Lett. 96, 086406.
- Hubbard, J., 1963, Proc. R. Soc. A 276, 238.
- Huse, D. A., Krauth, R. Moessner, and S. L. Sondhi, 2003, Phys. Rev. Lett. 91, 167004.
- Imada, M., A. Fujimori, and Y. Tokura, 1998, Rev. Mod. Phys. 70, 1039.
- Ioffe, L. B., and A. I. Larkin, 1989, Phys. Rev. B 40, 6941.
- Isacsson, A., and S. M. Girvin, 2005, Phys. Rev. A 72, 053604.
- Ishihara, S., T. Tanaka, and M. Matsumoto, 2007, J. Mol. Struct. 838, 216.
- Jackeli, G., and G. Khaliullin, 2009, Phys. Rev. Lett. 102, 017205.
- Jahn, H., and E. Teller, 1937, Proc. R. Soc. A 161, 220.
- Jaksch, D., C. Bruder, J. I. Cirac, C. W. Gardiner, and P. Zoller, 1998, Phys. Rev. Lett. 81, 3108.
- Jaksch, D., and P. Zoller, 2005, Ann. Phys. (N.Y.) 315, 52.
- Kanamori, J., 1959, J. Phys. Chem. Solids 10, 87.
- Kanamori, J., 1960, J. Appl. Phys. 31, S14.
- Kargarian, M., A. Langari, and G. A. Fiete, 2012, Phys. Rev. B 86, 205124.
- Khaliullin, G., 2001, Phys. Rev. B 64, 212405.
- Khaliullin, G., 2005, Prog. Theor. Phys. Suppl. 160, 155.
- Khaliullin, G., P. Horsch, and A. M. Oleś, 2001, Phys. Rev. Lett. 86, 3879.
- Khaliullin, G., and S. Maekawa, 2000, Phys. Rev. Lett. 85, 3950.
- Khaliullin, G., and V. Oudovenko, 1997, Phys. Rev. B 56, R14243.
- Khomskii, D., 2010, Basic Aspects of the Quantum Theory of Solids: Order and Elementary Excitations (Cambridge University Press, Cambridge, England).
- Kitaev, A. Y., 2003, Ann. Phys. (Amsterdam) 303, 2.
- Kitaev, A. Y., 2006, Ann. Phys. (Amsterdam) 321, 2.
- Kivelson, S. A., D. S. Rokhsar, and J. P. Sethna, 1987, Phys. Rev. B 35, 8865.
- Kogut, J. B., 1979, Rev. Mod. Phys. 51, 659.
- Köhl, M., H. Moritz, T. Stöferle, K. Günter, and T. Esslinger, 2005, Phys. Rev. Lett. 94, 080403.
- Kruger, F., S. Kumar, J. Zaanen, and J. van den Brink, 2009, Phys. Rev. B 79, 054504.
- Kubo, K., 2002, J. Phys. Soc. Jpn. 71, 1308.
- Kugel, K., and D. Khomskii, 1972, JETP Lett. 15, 446.
- Kugel, K., and D. Khomskii, 1973, Sov. Phys. JETP 37, 725.
- Kugel, K., and D. Khomskii, 1982, Sov. Phys. Usp. 25, 231.
- Kuklov, A. B., 2006, Phys. Rev. Lett. 97, 110405.
- Kuklov, A. B., and B. V. Svistunov, 2003, Phys. Rev. Lett. 90, 100401.
- Kuroki, K., S. Onari, R. Arita, H. Usui, Y. Tanaka, H. Kotani, and H. Aoki, 2008, Phys. Rev. Lett. 101, 087004.
- Lai, H.-H., and O. I. Motrunich, 2011, Phys. Rev. B 84, 235148.
- Lieb, E., 1967, Phys. Rev. 162, 162.
- Lieb, E., 1973, Commun. Math. Phys. 31, 327.
- Lieb, E., T. Schultz, and D. Mattis, 1961, Ann. Phys. (N.Y.) 16, 407.
- Lin, F., and V. W. Scarola, 2013, Phys. Rev. Lett. 111, 220401.
- Liu, W. V., and C. Wu, 2006, Phys. Rev. A 74, 013607.
- Lo, K. W., W.-C. Lee, and P. W. Phillips, 2013, Europhys. Lett. 101, 50007.
- Lou, J., A. W. Sandvik, and L. Balents, 2007, Phys. Rev. Lett. 99, 207203.
- Luttinger, J. M., and L. Tisza, 1946, Phys. Rev. 70, 954.
- Lv, W., J. Wu, and P. Phillips, 2009, Phys. Rev. B 80, 224506.
- Lyons, D. H., and T. A. Kaplan, 1960, Phys. Rev. 120, 1580.
- Ma, S.-K., 1973, Phys. Rev. A 7, 2172.
- MacDonald, A. H., and M. P. A. Fisher, 2000, Phys. Rev. B 61, 5724.
- Matsubara, T., and H. Matsuda, 1956, Prog. Theor. Phys. 16, 569.
- Micheli, A., G. K. Brennen, and P. Zoller, 2006, Nat. Phys. 2, 341.
- Mila, F., 1998, Phys. Rev. Lett. 81, 2356.
- Mila, F., F. Vernay, A. Ralko, F. Becca, P. Fazekas, and K. Penc, 2007, J. Phys. Condens. Matter 19, 145201.
- Mishra, A., M. Ma, F.-C. Zhang, S. Guertler, L.-H. Tang, and S. Wan, 2004, Phys. Rev. Lett. 93, 207201.
- Moessner, R., 2001, Can. J. Phys. 79, 1283.
- Mondal, S., D. Sen, and K. Sengupta, 2008, Phys. Rev. B 78, 045101.
- Moore, J. E., and D.-H. Lee, 2004, Phys. Rev. B 69, 104511.
- Mostovoy, M. V., and D. I. Khomskii, 2002, Phys. Rev. Lett. 89, 227203.
- Mostovoy, M. V., and D. I. Khomskii, 2004, Phys. Rev. Lett. 92, 167201.
- Motome, Y., and H. Tsunetsugu, 2004, Phys. Rev. B 70, 184427.
- Mott, N. F., 1990, Metal-Insulator Transitions (Taylor & Francis, London).
- Mross, D. F., A. Essin, and J. Alicea, 2014, arXiv:1410.4201.
- Müller, T., S. Fölling, A. Widera, and I. Bloch, 2007, Phys. Rev. Lett. 99, 200405.
- Murakami, Y., H. Kawada, H. Kawata, M. Tanaka, T. Arima, Y. Moritomo, and Y. Tokura, 1998, Phys. Rev. Lett. 80, 1932.
- Nagle, J. F., 1966, J. Math. Phys. (N.Y.) 7, 1484.
- Nakayama, K., et al., 2009, Europhys. Lett. 85, 67002.
- Nasu, J., and S. Ishihara, 2011a, J. Phys. Conf. Ser. 320, 012062.
- Nasu, J., and S. Ishihara, 2011b, J. Phys. Conf. Ser. 320, 012062.
- Nasu, J., and S. Ishihara, 2011c, J. Phys. Soc. Jpn. 80, 033704.
- Nasu, J., and S. Ishihara, 2012, Europhys. Lett. 97, 27002.
- Nasu, J., A. Nagano, M. Naka, and S. Ishihara, 2008, Phys. Rev. B 78, 024416.
- Nasu, J., S. Todo, and S. Ishihara, 2012a, Phys. Rev. B 85, 205141.
- Nasu, J., S. Todo, and S. Ishihara, 2012b, Phys. Rev. B 85, 205141.
- Nogueira, F. S., and Z. Nussinov, 2009, Phys. Rev. B 80, 104413.
- Normand, B., and Z. Nussinov, 2014, Phys. Rev. Lett. 112, 207202.
- Nussinov, Z., 2001, arXiv:cond-mat/0105253.
- Nussinov, Z., 2004, Phys. Rev. B 69, 014208.
- Nussinov, Z., 2005, Phys. Rev. D 72, 054509.
- Nussinov, Z., 2006, arXiv:cond-mat/0606075.
- Nussinov, Z., C. Batista, and E. Fradkin, 2006, Int. J. Mod. Phys. B 20, 5239.
- Nussinov, Z., C. D. Batista, B. Normand, and S. A. Trugman, 2007, Phys. Rev. B 75, 094411.
- Nussinov, Z., M. Biskup, L. Chayes, and J. van den Brink, 2004, Europhys. Lett. 67, 990.
- Nussinov, Z., and E. Fradkin, 2005, Phys. Rev. B 71, 195120.
- Nussinov, Z., and G. Ortiz, 2008, Europhys. Lett. 84, 36005.
- Nussinov, Z., and G. Ortiz, 2009a, Ann. Phys. (Amsterdam) 324, 977.
- Nussinov, Z., and G. Ortiz, 2009b, Phys. Rev. B 79, 214440.
- Nussinov, Z., and G. Ortiz, 2009c, Proc. Natl. Acad. Sci. U.S.A. 106, 16944.
- Nussinov, Z., G. Ortiz, and E. Cobanera, 2012a, Phys. Rev. B 86, 085415.
- Nussinov, Z., G. Ortiz, and E. Cobanera, 2012b, Ann. Phys. (Amsterdam) 327, 2491.
- Nussinov, Z., J. Rudnick, S. A. Kivelson, and L. N. Chayes, 1999, Phys. Rev. Lett. 83, 472.
- Nussinov, Z., and K. Shtengel, 2015, unpublished.
- Nussinov, Z., and J. van den Brink, 2013, arXiv:1303.5922.
- Nussinov, Z., and J. van den Brink, 2015, unpublished.
- O’Hern, C. S., and T. C. Lubensky, 1998, Phys. Rev. E 58, 5948.
- O’Hern, C. S., T. C. Lubensky, and J. Toner, 1999, Phys. Rev. Lett. 83, 2745.
- Oitmaa, J., and C. J. Hamer, 2011, Phys. Rev. B 83, 094437.
- Oleś, A., L. Feiner, and J. Zaanen, 2000, Phys. Rev. B 61, 6257.
- Oleś, A., G. Khaliullin, P. Horsch, and L. Feiner, 2005, Phys. Rev. B 72, 214431.
- Oleś, A. M., 1983, Phys. Rev. B 28, 327.
- Oleś, A. M., 2012, J. Phys. Condens. Matter 24, 313201.
- Ortiz, G., E. Cobanera, and Z. Nussinov, 2012, Nucl. Phys. B854, 780.
- Orús, R., A. C. Doherty, and G. Vidal, 2009, Phys. Rev. Lett. 102, 077203.
- Paglione, J., and R. L. Greene, 2010, Nat. Phys. 6, 645.
- Paramekanti, A., L. Balents, and M. P. A. Fisher, 2002, Phys. Rev. B 66, 054526.
- Pedrocchi, F. L., S. Chesi, S. Gangadharaiah, and D. Loss, 2012, Phys. Rev. B 86, 205412.
- Perez-Garcia, D., M. M. Wolf, M. Sanz, F. Verstraete, and J. I. Cirac, 2008, Phys. Rev. Lett. 100, 167202.
- Powell, S., 2011, Phys. Rev. B 84, 094437.
- Rastelli, E., and A. Tassi, 1987, J. Phys. C 20, L303.
- Reitsma, A. J. W., L. F. Feiner, and A. M. Oleś, 2005, New J. Phys. 7, 121.
- Reuther, J., R. Thomale, and S. Trebst, 2011, Phys. Rev. B 84, 100406(R).
- Rokshar, D. S., and S. A. Kivelson, 1988, Phys. Rev. Lett. 61, 2376.
- Rousochatazakis, I., U. K. Rossler, J. van den Brink, and M. Daghofer, 2013, arXiv:1209.5895.
- Sachdev, S., 1999, Quantum Phase Transitions (Cambridge University Press, London).
- Saket, A., S. R. Hassan, and R. Shankar, 2010, Phys. Rev. B 82, 174409.
- Scarola, V. W., K. B. Whaley, and M. Troyer, 2009, Phys. Rev. B 79, 085113.
- Schneider, U., L. Hackermüller, S. Will, T. Best, I. Bloch, T. A. Costi, R. W. Helmes, D. Rasch, and A. Rosch, 2008, Science 322, 1520.
- Schultz, T. D., D. C. Mattis, and E. H. Lieb, 1964, Rev. Mod. Phys. 36, 856.
- Sen, D., and S. Vishveshwara, 2010, Europhys. Lett. 91, 66009.
- Serral Gracia, R., and T. M. Nieuwenhuizen, 2004, Phys. Rev. E 69, 056119.
- Shender, E., 1982, Sov. Phys. JETP 56, 178.
- Simon, B., 1980, Commun. Math. Phys. 71, 247.
- Stanley, H. E., 1968, Phys. Rev. 176, 718.
- Stillinger, F., and M. A. Cotter, 1973, J. Chem. Phys. 58, 2532.
- Stinhcombe, R., 1983, Phase Transition and Critical Phenomena, edited by C. Domb and J. L. Lebowitz, Vol. 7 (Academic Press, London).
- Stöferle, T., H. Moritz, C. Schori, M. Köhl, and T. Esslinger, 2004, Phys. Rev. Lett. 92, 130403.
- Sun, K.-W., Y.-Y. Zhang, and Q.-H. Chen, 2008, Phys. Rev. B 78, 184406.
- Tanaka, T., and S. Ishihara, 2007, Phys. Rev. Lett. 98, 256402.
- Tanaka, T., and S. Ishihara, 2009, Phys. Rev. B 79, 035109.
- Tanaka, T., M. Matsumoto, and S. Ishihara, 2005, Phys. Rev. Lett. 95, 267204.
- Tokura, Y., 2006, Rep. Prog. Phys. 69, 797.
- Tokura, Y., and N. Nagaosa, 2000, Science 288, 462.
- Tokura, Y., and Y. Tomioka, 1999, J. Magn. Magn. Mater. 200, 1.
- Trousselet, F., G. Khaliullin, and P. Horsch, 2011, Phys. Rev. B 84, 054409.
- Trousselet, F., A. M. Oleś, and P. Horsch, 2010, Europhys. Lett. 91, 40005.
- Trousselet, F., A. M. Oleś, and P. Horsch, 2012, Phys. Rev. B 86, 134412.
- Tsunetsugu, H., 2001, J. Phys. Soc. Jpn. 70, 640.
- van den Brink, J., 2004, New J. Phys. 6, 201.
- van den Brink, J., P. Horsch, F. Mack, and A. Oleś, 1999, Phys. Rev. B 59, 6795.
- van den Brink, J., G. Khaliullin, and D. Khomskii, 2004, Orbital Effects in Manganites and in Colossal Magnetoresistive Manganites, edited by T. Chatterji (Kluwer Academic Publishers, Dordrecht).
- van den Brink, J., and D. Khomskii, 1999, Phys. Rev. Lett. 82, 1016.
- van den Brink, J., M. B. J. Meinders, J. Lorenzana, R. Eder, and G. A. Sawatzky, 1995, Phys. Rev. Lett. 75, 4658.
- van Rynbach, A., S. Todo, and S. Trebst, 2010, Phys. Rev. Lett. 105, 146402.
- Venderbos, J. W. F., M. Daghofer, J. van den Brink, and S. Kumar, 2011, Phys. Rev. Lett. 107, 076405.
- Vernay, F., K. Penc, and F. Mila, 2004, Phys. Rev. B 70, 014428.
- Villain, J., 1972, Solid State Commun. 10, 967.
- Villain, J., R. Bidaux, J. P. Carton, and R. Conte, 1980, J. Phys. (Paris) 41, 1263.
- Vishwanath, A., and D. Carpentier, 2001, Phys. Rev. Lett. 86, 676.
- Wegner, F., 1971, J. Math. Phys. (N.Y.) 12, 2259.
- Weimer, H., 2013, Mol. Phys. 111, 1753.
- Weisse, A., and H. Fehske, 2004, New J. Phys. 6, 158.
- Wen, X.-G., 2004, Quantum Field Theory of Many-Body Systems (Oxford University Press, Oxford).
- Wenzel, S., and W. Janke, 2008, Phys. Rev. B 78, 064402.
- Wenzel, S., and W. Janke, 2009, Phys. Rev. B 80, 054403.
- Wenzel, S., W. Janke, and A. M. Läuchli, 2010, Phys. Rev. E 81, 066702.
- Wenzel, S., and A. M. Läuchli, 2011a, J. Stat. Mech. P09010.
- Wenzel, S., and A. M. Läuchli, 2011b, Phys. Rev. Lett. 106, 197201.
- Wohlfeld, K., M. Daghofer, and A. M. Oleś, 2011, Europhys. Lett. 96, 27001.
- Wu, C., 2008, Phys. Rev. Lett. 100, 200406.
- Wu, C., and S. Das Sarma, 2008, Phys. Rev. B 77, 235107.
- Wu, C., W. V. Liu, J. Moore, and S. Das Sarma, 2006, Phys. Rev. Lett. 97, 190406.
- Wu, K., and H. Zhai, 2008, Phys. Rev. B 77, 174431.
- Xu, C., and J. E. Moore, 2004, Phys. Rev. Lett. 93, 047003.
- Xu, C., and J. E. Moore, 2005, Nucl. Phys. B716, 487.
- You, W.-L., and G.-S. Tian, 2008, Phys. Rev. B 78, 184406.
- Youngblood, R. W., and J. D. Axe, 1981, Phys. Rev. B 23, 232.
- Zaanen, J., G. A. Sawatsky, and J. W. Allen, 1985, Phys. Rev. Lett. 55, 418.
- Zhao, E., and W. V. Liu, 2008, Phys. Rev. Lett. 100, 160403.