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Disorder at first-order classical and quantum phase transitions

Ahmed K. Ibrahim

Jan 1, 20180 citations

Rounding the First-Order Quantum Phase Transitions by Disorder in the Quantum Ashkin-Teller Model

Ahmed K. Ibrahim, Thomas Vojta

Bulletin of the American Physical SocietyMar 13, 20170 citations

Edge Magnon Excitation in Spin Dimer Systems

Ryo Sakaguchi, M. Matsumoto

Magnetic excitation in a spin dimer system on a bilayer honeycomb lattice is investigated in the presence of a zigzag edge, where disordered and ordered phases can be controlled by a quantum phase transition. In analogy with the case of graphene with a zigzag edge, a flat edge magnon mode appears in the disordered phase. In an ordered phase, a finite magnetic moment generates a mean-field potential to the magnon. Since the potential is nonuniform on the edge and bulk sites, it affects the excitation, and the dispersion of the edge mode deviates from the flat shape. We investigate how the edge magnon mode evolves when the phase changes through the quantum phase transition and discuss the similarities to ordered spin systems on a monolayer honeycomb lattice.Magnetic excitation in a spin dimer system on a bilayer honeycomb lattice is investigated in the presence of a zigzag edge, where disordered and ordered phases can be controlled by a quantum phase transition. In analogy with the case of graphene with a zigzag edge, a flat edge magnon mode appears in the disordered phase. In an ordered phase, a finite magnetic moment generates a mean-field potential to the magnon. Since the potential is nonuniform on the edge and bulk sites, it affects the excitation, and the dispersion of the edge mode deviates from the flat shape. We investigate how the edge magnon mode evolves when the phase changes through the quantum phase transition and discuss the similarities to ordered spin systems on a monolayer honeycomb lattice.

arXiv:1610.04333Journal of the Physical Society of JapanSep 12, 20167 citations

First-order quantum phase transitions

M. A. Contínentino, André S. Ferreira

arXiv:cond-mat/0610624Journal of Magnetism and Magnetic MaterialsNov 17, 20069 citations

Disorder-Driven Quantum Phase Transitions in Superconductors and Magnets

L. B. Ioffe, Marc Mézard

We develop an analytical theory, based on the quantum cavity method, describing the quantum phase transitions in low-temperature, strongly disordered ferromagnets and superconductors. At variance with the usual quantum critical points, we find a phase diagram with two critical points separating three phases. When the disorder increases, the systems goes from the ordered phase to an intermediate disordered phase characterized by activated transport and then to a second disordered phase where no transport is possible. Both the ordered and disordered phases exhibit strong inhomogeneity of their basic properties typical of glassy physics.We develop an analytical theory, based on the quantum cavity method, describing the quantum phase transitions in low-temperature, strongly disordered ferromagnets and superconductors. At variance with the usual quantum critical points, we find a phase diagram with two critical points separating three phases. When the disorder increases, the systems goes from the ordered phase to an intermediate disordered phase characterized by activated transport and then to a second disordered phase where no transport is possible. Both the ordered and disordered phases exhibit strong inhomogeneity of their basic properties typical of glassy physics.

arXiv:0909.2263Physical Review LettersJul 14, 201081 citations

Quantum phase transitions in the presence of disorder and dissipation

Chetan Kotabage

Jan 1, 20111 citation

Quantum phase transitions generated by order from quantum disorder

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