title: Quantum criticality with two length scales.
abstract: The theory of deconfined quantum critical (DQC) points describes phase transitions at absolute temperature T = 0 outside the standard paradigm, predicting continuous transformations between certain ordered states where conventional theory would require discontinuities. Numerous computer simulations have offered no proof of such transitions, instead finding deviations from expected scaling relations that neither were predicted by the DQC theory nor conform to standard scenarios. Here we show that this enigma can be resolved by introducing a critical scaling form with two divergent length scales. Simulations of a quantum magnet with antiferromagnetic and dimerized ground states confirm the form, proving a continuous transition with deconfined excitations and also explaining anomalous scaling at T > 0. Our findings revise prevailing paradigms for quantum criticality, with potential implications for many strongly correlated materials.
authors.affiliation: Department of Physics, Beijing Normal University, Beijing 100875, China. Beijing Computational Science Research Center, Beijing 100084, China. Department of Physics, Boston University, Boston, MA 02215, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Shao
authors.affiliation: Department of Physics, Beijing Normal University, Beijing 100875, China. State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China. waguo@bnu.edu.cn sandvik@bu.edu.
authors.forename: Wenan
authors.initials: W
authors.lastname: Guo
authors.affiliation: Department of Physics, Boston University, Boston, MA 02215, USA. waguo@bnu.edu.cn sandvik@bu.edu.
authors.forename: Anders W
authors.initials: AW
authors.lastname: Sandvik