Dr Christian Rüegg London Centre for Nanotechnology and Department of Physics and Astronomy, University College London

Jeudi 09 Septembre à 16 h 00 Amphi Boreau, Esc. C, 1er étage
Exploring Exotic Quantum Phases in Model Magnets

Quantum spins in magnets show a cornucopia of complex quantum phases at low temperatures including for example Bose-Einstein Condensates, spin Luttinger-liquids, and supersolids [1]. Direct control of the magnetic exchange interactions and fluctuations by application of hydrostatic pressure [2] or magnetic field [3-5] allows us to study these phases in real materials and by a number of experimental techniques. Here, quasi-one-dimensional arrays of quantum spin ladders are particularly exciting because they show a rich phase diagram in temperature and magnetic field. In the seminar I will present our most recent work, in which we have been able to explore quantum disordered, quantum critical, spin Luttinger-liquid, BEC, and classically saturated regimes and their thermodynamics and characteristic excitations in novel metal-organic compounds [3-5]. The results will be discussed in the context of developments and future perspectives in neutron spectroscopy, crystal growth of novel custom-built materials, and challenges in quantum many-body theory.

[1] T. Giamarchi, Ch. Rüegg, O. Tchernyshyov, Nature Physics 4, 198 (2008).
[2] Ch. Rüegg et al., Phys. Rev. Lett. 100, 205701 (2008).
[3] Ch. Rüegg et al., Phys. Rev. Lett. 101, 247202 (2008).
[4] B. Thielemann et al., Phys. Rev. B 79, 020408(R) (2009).
[5] B. Thielemann et al., Phys. Rev. Lett. 102, 107204 (2009).

Pour tout renseignement :
N. Bergeal : 01 40 79 44 83 – nicolas.bergeal (arobase) espci.fr
B. Fauqué 01 40 79 58 14 –benoit.fauque (arobase) espci.fr

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