Magnetic field-induced quasiparticle instability and universal scaling behavior at finite fields in an S=1/2 quantum antiferromagnet

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Event Details
  • Date/Time:
    • Thursday April 7, 2016 - Friday April 8, 2016
      3:00 pm - 3:59 pm
  • Location: Howey N110
  • Phone: (404) 894-8886
  • URL:
  • Email:
  • Fee(s):
    Free
  • Extras:
Contact

amorain@gatech.edu

Summaries

Summary Sentence: Magnetic field-induced quasiparticle instability and universal scaling behavior at finite fields in an S=1/2 quantum antiferromagnet

Full Summary: No summary paragraph submitted.

Quasiparticles, such as phonons, magnons, rotons, and heavy electrons and holes, are ubiquitous in nature. Quasiparticles usually have a long lifetime due to the weak or absence of interactions between them. However, this picture breaks down in rare conditions. In this talk, I will describe the experimental realization of magnetic field-induced spontaneous (T=0) magnon decays in an S=1/2 quantum antiferromagnet C9H18N2CuBr4 using the neutron scattering techniques [1]. The observed intriguing renormalization of one-magnon dispersion and magnon decays over a large region of the Brillouin Zone in the magnetic excitation specra can be well explained by the mechanism where the three-magnon interactions are present and the process of one-magnon decays into the two-magnon continuum is kinematically allowed [2]. Moreover, I will show that a universal scaling of the field-dependence of the Zeeman energy behaves in the same way as the temperature dependence of the spin gap in one-dimensional quantum magnets and agrees well with the calculation by the non-linear sigma model [3]. This result demonstrates the similarity between thermal and quantum fluctuations near the quantum critical point [4], where the intrinsic energy scales vanish.

 Reference:

[1] T. Hong et al., submitted.

[2] M. E. Zhitomirsky and A. L. Chernyshev, Rev. Mod. Phys. 85, 219 (2013).

[3] K. Damle and S. Sachdev, Phys. Rev. B 57, 8307 (1998).

[4] S. Sachdev, Quantum Phase Transitions, Cambridge University Press (2001).

 

Additional Information

In Campus Calendar
Yes
Groups

School of Physics

Invited Audience
Undergraduate students, Faculty/Staff, Graduate students
Categories
Seminar/Lecture/Colloquium
Keywords
School of Physics, seminar
Status
  • Created By: Alison Morain
  • Workflow Status: Published
  • Created On: Mar 7, 2016 - 7:55am
  • Last Updated: Apr 13, 2017 - 5:16pm