1.
Vachon, Marc-Andre.
Nuclear Magnetic Resonance Study of the Magnetism in the 2D
Frustrated Quantum Heisenberg Antiferromagnet Cs2CuCl4.
Degree: PhD, Physics, 2009, Brown University
URL: https://repository.library.brown.edu/studio/item/bdr:93/
The experimental realization of a two dimensional
quantum spin liquid has been eagerly sought since first proposed by
Anderson in 1973. Recently, Cs2CuCl4, a frustrated 2D quantum
antiferromagnet (QAF), has shown potential in this regard
triggering immense interest, both experimentally and theoretically.
Amongst these studies, different scenarios on the nature of the
spin liquid phase were proposed and the presence of exotic magnetic
phases in the ground state was noticed. To this date, many of these
phases are still obscured and the nature of the spin liquid state
remains unsettled. To investigate the above, we present 133Cs
Nuclear Magnetic Resonance (NMR)measurements on Cs2CuCl4 at
temperature down to 50mK and applied magnetic field up to 15 T. We
first demonstrate that Cs NMR is an effective probe of the
magnetism in the compound through experiments in the paramagnetic
phase. Lower temperature NMR measurements as a function of the
strength and orientation of the applied magnetic field provide the
most complete picture of the different phases stabilized in
Cs2CuCl4. The magnetic character of these phases is discussed in
the context of the interplay between quantum fuctuations,
frustration and the Dzyaloshinskii-Moriya (DM) interaction.
Furthermore, we find evidence of three new phase transitions, as
well as an unexpected angular dependence of the saturation field.
These findings suggest that the accepted Hamiltonian requires
modifications, such as additional DM interactions. In order to
probe the nature of the spin liquid state, local magnetization and
spin-lattice relaxation rate measurements were performed. A
comparison with the result of a variational calculation using
Gutzwiller-projected mean-field theory demonstrates the 2D magnetic
behavior of the local magnetization. In addition, both temperature
and magnetic field dependence of the spin-lattice relaxation rate
suggests that the relevant low energy quasiparticle excitations
obey fermionic statistics.
Advisors/Committee Members: Mitrovic, Vesna (director), Marston, J. (reader), Valles, James (reader).
Subjects/Keywords: NMR
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APA (6th Edition):
Vachon, M. (2009). Nuclear Magnetic Resonance Study of the Magnetism in the 2D
Frustrated Quantum Heisenberg Antiferromagnet Cs2CuCl4. (Doctoral Dissertation). Brown University. Retrieved from https://repository.library.brown.edu/studio/item/bdr:93/
Chicago Manual of Style (16th Edition):
Vachon, Marc-Andre. “Nuclear Magnetic Resonance Study of the Magnetism in the 2D
Frustrated Quantum Heisenberg Antiferromagnet Cs2CuCl4.” 2009. Doctoral Dissertation, Brown University. Accessed January 26, 2021.
https://repository.library.brown.edu/studio/item/bdr:93/.
MLA Handbook (7th Edition):
Vachon, Marc-Andre. “Nuclear Magnetic Resonance Study of the Magnetism in the 2D
Frustrated Quantum Heisenberg Antiferromagnet Cs2CuCl4.” 2009. Web. 26 Jan 2021.
Vancouver:
Vachon M. Nuclear Magnetic Resonance Study of the Magnetism in the 2D
Frustrated Quantum Heisenberg Antiferromagnet Cs2CuCl4. [Internet] [Doctoral dissertation]. Brown University; 2009. [cited 2021 Jan 26].
Available from: https://repository.library.brown.edu/studio/item/bdr:93/.
Council of Science Editors:
Vachon M. Nuclear Magnetic Resonance Study of the Magnetism in the 2D
Frustrated Quantum Heisenberg Antiferromagnet Cs2CuCl4. [Doctoral Dissertation]. Brown University; 2009. Available from: https://repository.library.brown.edu/studio/item/bdr:93/