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Some magnets are exceptional solid-state model systems for high-precision studies of fundamental quantum phenomena in physics like Bose-Einstein condensates and Tomonaga-Luttinger liquids [1,2]. Further examples include complex ground states and correlations realized in low-dimensional and frustrated systems [3,4], exciting physics of impurities and quenched disorder [5], and dramatic events near quantum phase transitions [6]. In this colloquium studies of model oxides and halides by neutron scattering and complementary experimental techniques will be presented. Classical phase transitions in such compounds can be controlled easily by temperature, interactions and quantum fluctuations by chemistry and pressure application, and correlations and particle numbers by magnetic field. The experimental results will be discussed in the context of recent developments of powerful computational methods enabling fully quantitative analysis and of related work on other model systems like gases of ultracold atoms. [1] T. Giamarchi et al., Nature Physics 4, 198 (2008). [2] B. Thielemann et al., Phys. Rev. Lett. 102, 107204 (2009). [3] Y. Kohama et al., Phys. Rev. Lett. 109, 167204 (2012). [4] F. Casola et al., Phys. Rev. Lett. 110, 187201 (2013). [5] S. Ward et al., J. Phys.: Condens. Matter 25, 014004 (2013). [6] P. Merchant et al., Nature Physics, in press (2014).

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Christian Rüegg, Paul Scherrer Institute, University of Geneva
Seminar Room of the Institute of Physics II (R201)
Contact: Simon Trebst