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SUMMARY:Tunable States in a Model Quantum Magnet
DTSTART:20160324T113000
DTEND:20160324T123000
DTSTAMP:20260407T181209Z
UID:e9e7d012b24c81f6288fe9b40a667b00cbf9f64add107d9bbdb177c1
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Daniel M. SILEVITCH (Caltech\, Pasadena\, USA)\nChanging t
 he ground state of a system via a non-thermal parameter such as doping or 
 pressure has been a topic of great interest in condensed matter physics fo
 r decades\, most notably in the study of quantum phase transitions and the
  associated quantum critical regime. The rare-earth fluoride LiHoF_4 and t
 he related dilution series LiHo_{1-x}Y_xF4\, long known to be a realizatio
 n of the S=1/2 Transverse Ising Model\, can be used to study state tuning 
 as a function of several tuning parameters. In addition to the well-unders
 tood field-induced ferromagnet to paramagnet quantum phase transition in p
 ure LiHoF_4\, there are a number of subtler transitions which are seen in 
 the diluted materials. For x~=0.5\, application of a magnetic field transv
 erse to the Ising axis transitions the system into a realization of the Ra
 ndom-Field Ising Model\, an important generic model for studying the effec
 ts of disorder. In the more highly dilution limit\, at x~0.05\, ordered fe
 rromagnetic states are no longer stable due to frustration effects. Instea
 d\, the system shows behavior consistent with either a spin glass or a non
 -freezing spin liquid\, and can be tuned between these two regimes by vary
 ing the degree of thermal connectivity with an external heat bath or by tu
 ning the rate of quantum tunneling via an external magnetic field. Further
 \, the behavior of nonlinear excitations can be continuously tuned by exte
 rnal fields\, including the ability to largely decouple the excitations fr
 om the background spin environment.
LOCATION:PH L1 503 http://plan.epfl.ch/?request_locale=en&room=ph+l1+503&d
 omain=places
STATUS:CONFIRMED
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