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Unbounded Derivations Of C*-Algebras And The Heisenberg Commutation Relation, Lara M. Ismert
Unbounded Derivations Of C*-Algebras And The Heisenberg Commutation Relation, Lara M. Ismert
Department of Mathematics: Dissertations, Theses, and Student Research
This dissertation investigates the properties of unbounded derivations on C*-algebras, namely the density of their analytic vectors and a property we refer to as "kernel stabilization." We focus on a weakly-defined derivation δD which formalizes commutators involving unbounded self-adjoint operators on a Hilbert space. These commutators naturally arise in quantum mechanics, as we briefly describe in the introduction.
A first application of kernel stabilization for δD shows that a large class of abstract derivations on unbounded C*-algebras, defined by O. Bratteli and D. Robinson, also have kernel stabilization. A second application of kernel stabilization provides a sufficient condition …
Random-Field Critical And Spin-Flop Behavior Of The Anisotropic Heisenberg Antiferromagnet Fe0.9mg0.1br2 In Axial Magnetic Fields, Christian Binek
Random-Field Critical And Spin-Flop Behavior Of The Anisotropic Heisenberg Antiferromagnet Fe0.9mg0.1br2 In Axial Magnetic Fields, Christian Binek
Christian Binek Publications
Faraday optical measurements on the dilute hexagonal antiferromagnet Fe0.85Mg0.15Br2 in an external axial field reveal a spin-flop phase line ending at a multicritical point (Tm=8.1 K, Hm=1050 kA m-1) and crossover from random-exchange to random-field Ising criticality with an exponent Phi =1.40+or-0.04 in the vicinity of TN=11.1 K. Cusp-like behaviour of the specific heat at TN is discussed in view of recent Monte Carlo results.