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Levitin LV, van der Vliet H, Theisen T, Dimitriadis S, Lucas M, Corcoles AD, Nyéki J, Casey AJ, Creeth G, Farrer I, Ritchie DA, Nicholls JT, Saunders J. Cooling low-dimensional electron systems into the microkelvin regime. Nat Commun 2022; 13:667. [PMID: 35115494 PMCID: PMC8814190 DOI: 10.1038/s41467-022-28222-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 12/14/2021] [Indexed: 12/03/2022] Open
Abstract
Two-dimensional electron gases (2DEGs) with high mobility, engineered in semiconductor heterostructures host a variety of ordered phases arising from strong correlations, which emerge at sufficiently low temperatures. The 2DEG can be further controlled by surface gates to create quasi-one dimensional systems, with potential spintronic applications. Here we address the long-standing challenge of cooling such electrons to below 1 mK, potentially important for identification of topological phases and spin correlated states. The 2DEG device was immersed in liquid 3He, cooled by the nuclear adiabatic demagnetization of copper. The temperature of the 2D electrons was inferred from the electronic noise in a gold wire, connected to the 2DEG by a metallic ohmic contact. With effective screening and filtering, we demonstrate a temperature of 0.9 ± 0.1 mK, with scope for significant further improvement. This platform is a key technological step, paving the way to observing new quantum phenomena, and developing new generations of nanoelectronic devices exploiting correlated electron states.
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Affiliation(s)
- Lev V Levitin
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK.
| | - Harriet van der Vliet
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
- Oxford Instruments Nanoscience, Abingdon, Oxfordshire, OX13 5QX, UK
| | - Terje Theisen
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
| | - Stefanos Dimitriadis
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
- Department of Physics, Imperial College London, London, SW7 2AZ, UK
| | - Marijn Lucas
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
| | - Antonio D Corcoles
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
- Thomas J. Watson Research Center, Yorktown Heights, NY, 10598, USA
| | - Ján Nyéki
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
| | - Andrew J Casey
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
| | - Graham Creeth
- London Centre for Nanotechnology, University College London, London, WC1H 0AH, UK
- Praesto Consulting, Dublin, D02 A342, Ireland
| | - Ian Farrer
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
- Department of Electronic and Electrical Engineering, University of Sheffield, Sheffield, S1 3JD, UK
| | - David A Ritchie
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, CB3 0HE, UK
| | - James T Nicholls
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
| | - John Saunders
- Department of Physics, Royal Holloway, University of London, Egham, TW20 0EX, UK
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Shi Q, Shih EM, Gustafsson MV, Rhodes DA, Kim B, Watanabe K, Taniguchi T, Papić Z, Hone J, Dean CR. Odd- and even-denominator fractional quantum Hall states in monolayer WSe 2. NATURE NANOTECHNOLOGY 2020; 15:569-573. [PMID: 32632320 DOI: 10.1038/s41565-020-0685-6] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2019] [Accepted: 04/05/2020] [Indexed: 06/11/2023]
Abstract
Monolayer semiconducting transition-metal dichalcogenides (TMDs) represent a unique class of two-dimensional (2D) electron systems. Their atomically thin structure facilitates gate tunability just like graphene does, but unlike graphene, TMDs have the advantage of a sizable band gap and strong spin-orbit coupling. Measurements under large magnetic fields have revealed an unusual Landau level (LL) structure1-3, distinct from other 2D electron systems. However, owing to the limited sample quality and poor electrical contact, probing the lowest LLs has been challenging, and observation of electron correlations within the fractionally filled LL regime has not been possible. Here, through bulk electronic compressibility measurements, we investigate the LL structure of monolayer WSe2 in the extreme quantum limit, and observe fractional quantum Hall states in the lowest three LLs. The odd-denominator fractional quantum Hall sequences demonstrate a systematic evolution with the LL orbital index, consistent with generic theoretical expectations. In addition, we observe an even-denominator state in the second LL that is expected to host non-Abelian statistics. Our results suggest that the 2D semiconductors can provide an experimental platform that closely resembles idealized theoretical models in the quantum Hall regime.
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Affiliation(s)
- Qianhui Shi
- Department of Physics, Columbia University, New York, NY, USA
| | - En-Min Shih
- Department of Physics, Columbia University, New York, NY, USA
| | - Martin V Gustafsson
- Department of Physics, Columbia University, New York, NY, USA
- Raytheon BBN Technologies, Cambridge, MA, USA
| | - Daniel A Rhodes
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Bumho Kim
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Japan
| | | | - Zlatko Papić
- School of Physics and Astronomy, University of Leeds, Leeds, UK
| | - James Hone
- Department of Mechanical Engineering, Columbia University, New York, NY, USA
| | - Cory R Dean
- Department of Physics, Columbia University, New York, NY, USA.
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Schreiber KA, Samkharadze N, Gardner GC, Lyanda-Geller Y, Manfra MJ, Pfeiffer LN, West KW, Csáthy GA. Electron-electron interactions and the paired-to-nematic quantum phase transition in the second Landau level. Nat Commun 2018; 9:2400. [PMID: 29921969 PMCID: PMC6008478 DOI: 10.1038/s41467-018-04879-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 05/23/2018] [Indexed: 11/12/2022] Open
Abstract
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.
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Affiliation(s)
- K A Schreiber
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
| | - N Samkharadze
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
- QuTech and Kavli Institute of NanoScience, Delft University of Technology, Lorentzweg 1, 2628 CJ, Delft, Netherlands
| | - G C Gardner
- School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
| | - Y Lyanda-Geller
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
| | - M J Manfra
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
- School of Materials Engineering, Purdue University, West Lafayette, IN, 47907, USA
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA
- School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
| | - L N Pfeiffer
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - K W West
- Department of Electrical Engineering, Princeton University, Princeton, NJ, 08544, USA
| | - G A Csáthy
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA.
- Birck Nanotechnology Center, Purdue University, West Lafayette, IN, 47907, USA.
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