Electron–electron interactions and the paired-to-nematic quantum phase transition in the second Landau level

• Published in: Nature communications Vol. 9; no. 1; pp. 2400 - 7
• Main Authors: Schreiber, K. A., Samkharadze, N., Gardner, G. C., Lyanda-Geller, Y., Manfra, M. J., Pfeiffer, L. N., West, K. W., Csáthy, G. A.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19-06-2018; Nature Publishing Group; Nature Portfolio
• Subjects: 639/766/119/1000; 639/766/119/2794; 639/766/119/2795; 639/766/119/995; CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; Competition; Critical point; Electron gas; Electrons; Humanities and Social Sciences; multidisciplinary; Nematic; Phase transitions; Pressure; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-018-04879-1

In spite of its ubiquity in strongly correlated systems, the competition of paired and nematic ground states remains poorly understood. Recently such a competition was reported in the two-dimensional electron gas at filling factor
ν
 = 5/2. At this filling factor a pressure-induced quantum phase transition was observed from the paired fractional quantum Hall state to the quantum Hall nematic. Here we show that the pressure-induced paired-to-nematic transition also develops at
ν
 = 7/2, demonstrating therefore this transition in both spin branches of the second orbital Landau level. However, we find that pressure is not the only parameter controlling this transition. Indeed, ground states consistent with those observed under pressure also develop in a sample measured at ambient pressure, but in which the electron–electron interaction was tuned close to its value at the quantum critical point. Our experiments suggest that electron–electron interactions play a critical role in driving the paired-to-nematic transition.
Two-dimensional electron systems at half-filled Landau levels can form unusual electronic states such as paired fractional quantum Hall and nematic phases. Here the authors observe the transition between these two phases at filling factors 5/2 and 7/2 and demonstrate the important influence of interactions.