Direct observation of the Higgs amplitude mode in a two-dimensional quantum antiferromagnet near the quantum critical point...

by Tao Hong, Masashige Matsumoto, Y. Qiu, Wangchun Chen, Thomas Gentile, Shannon Watson, F. F. Awwadi, M. M. Turnbull, Sachith E Dissanayake, Harish K Agrawal, Rasmus Toft-petersen, Bastian Klemke, K Coester, K. Schmidt, David A Tennant