Higgs Amplitude Mode in a Two-Dimensional Quantum Antiferromagnet near the Quantum Critical Point0

Published

July 4, 2017

Author(s)

Tao Hong, Masashige Matsumoto, Yiming Qiu, Wangchun Chen, Thomas R. Gentile, Shannon M. Watson, Firas F. Awwadi, Mark M. Turnbull, Sachith E. Dissanayake, Harish Agrawal, Rasmus Toft-Petersen, Bastian Klemke, Kris Coester, Kai P. Schmidt, David A Tennant

Abstract

Spontaneous symmetry-breaking quantum phase transitions play an essential role in current condensed matter physics^1-3. The collective excitations in the broken-symmetry phase near the quantum critical point can be characterized by fluctuations of phase and amplitude of the order parameter. The phase oscillations correspond to the massless Nambu-Goldstone modes whereas the massive amplitude mode, analogous to the Higgs mode in the particle physics^4-6, is prone to decay into a pair of low-energy Nambu-Goldstone modes in low dimensions^2,7,8. The observation of a Higgs amplitude mode in low dimensions is an outstanding experimental challenge. Here, using the inelastic neutron scattering and application of the bond-operator theory, we directly and unambiguously identify the Higgs amplitude mode in a two-dimensional quantum S=1/2 coupled spin ladder compound C₉H₁₈N₂CuBr₄, which is located close to a quantum critical point. Owing to an anisotropic spin gap, it kinematically prevents such decay and the Higgs amplitude mode acquires an infinite lifetime.

Citation

Nature Physics

Volume

13

Pub Type

Journals

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Keywords

Higgs amplitude mode, quantum antiferromagnet, polarized neutron scattering

Citation

Hong, T. , Matsumoto, M. , Qiu, Y. , Chen, W. , Gentile, T. , Watson, S. , Awwadi, F. , Turnbull, M. , Dissanayake, S. , Agrawal, H. , Toft-Petersen, R. , Klemke, B. , Coester, K. , Schmidt, K. and Tennant, D. (2017), Higgs Amplitude Mode in a Two-Dimensional Quantum Antiferromagnet near the Quantum Critical Point0, Nature Physics, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=921983 (Accessed December 11, 2024)