Unconventional Anisotropic Even-Denominator Fractional Quantum Hall State in a System with Mass Anisotropy.

The fractional quantum Hall state (FQHS) observed at a half-filled Landau level in an interacting two-dimensional electron system (2DES) is among the most exotic states of matter as its quasiparticles are expected to be Majorana excitations with non-Abelian statistics. We demonstrate here the unexpected presence of such a state in a novel 2DES with a strong band-mass anisotropy. The FQHS we observe has unusual characteristics. While its Hall resistance is well quantized at low temperatures, it exhibits highly anisotropic in-plane transport resembling compressible stripe or nematic charge-density-wave phases. More striking, the anisotropy sets in suddenly below a critical temperature, suggesting a finite-temperature phase transition. Our observations highlight how anisotropy modifies the many-body phases of a 2DES, and should further fuel the discussion surrounding the enigmatic even-denominator FQHS.

[1]  K. West,et al.  Multivalley two-dimensional electron system in an AlAs quantum well with mobility exceeding 2×106cm2V−1s−1 , 2018, Physical Review Materials.

[2]  K. West,et al.  Electron–electron interactions and the paired-to-nematic quantum phase transition in the second Landau level , 2018, Nature Communications.

[3]  I. Sodemann,et al.  A cascade of phase transitions in an orbitally mixed half-filled Landau level , 2018, Science Advances.

[4]  F. Haldane,et al.  Pomeranchuk Instability of Composite Fermi Liquids. , 2018, Physical review letters.

[5]  M. Manfra,et al.  Possible nematic to smectic phase transition in a two-dimensional electron gas at half-filling , 2017, Nature Communications.

[6]  T. Taniguchi,et al.  Even-denominator fractional quantum Hall states in bilayer graphene , 2017, Science.

[7]  K. West,et al.  Design rules for modulation-doped AlAs quantum wells , 2017, 1707.09011.

[8]  I. Sodemann,et al.  Anisotropy-driven transition from the Moore-Read state to quantum Hall stripes , 2017, 1703.02167.

[9]  M. Shayegan,et al.  Transference of Fermi Contour Anisotropy to Composite Fermions. , 2017, Physical review letters.

[10]  T. Taniguchi,et al.  Tunable interacting composite fermion phases in a half-filled bilayer-graphene Landau level , 2016, Nature.

[11]  R. Cava,et al.  Observation of a nematic quantum Hall liquid on the surface of bismuth , 2016, Science.

[12]  W. Zhu,et al.  Fractional quantum Hall bilayers at half filling: Tunneling-driven non-Abelian phase , 2016, 1608.07761.

[13]  N. Regnault,et al.  Evidence of a fractional quantum Hall nematic phase in a microscopic model , 2016, 1607.02178.

[14]  A. Wójs,et al.  Landau-Level Mixing and Particle-Hole Symmetry Breaking for Spin Transitions in the Fractional Quantum Hall Effect. , 2016, Physical review letters.

[15]  M. Manfra,et al.  Evidence for a new symmetry breaking mechanism reorienting quantum Hall nematics , 2016, 1603.06864.

[16]  E. Fradkin,et al.  Nematic quantum phase transition of composite Fermi liquids in half-filled Landau levels and their geometric response , 2016, 1602.01482.

[17]  M. Manfra,et al.  Observation of a transition from a topologically ordered to a spontaneously broken symmetry phase , 2015, Nature Physics.

[18]  Kun Yang,et al.  Striped Quantum Hall State In A Half-filled Landau Level , 2015, 1509.01780.

[19]  M. Kawasaki,et al.  Even-denominator fractional quantum Hall physics in ZnO , 2015, Nature Physics.

[20]  V. O’Flaherty,et al.  Effect of sulfate on low-temperature anaerobic digestion , 2014, Front. Microbiol..

[21]  R. Winkler,et al.  Fermi contour anisotropy of GaAs electron-flux composite fermions in parallel magnetic fields , 2013, 1308.1728.

[22]  R. Willett,et al.  The quantum Hall effect at 5/2 filling factor , 2013, Reports on progress in physics. Physical Society.

[23]  S. Sondhi,et al.  Field theory of the quantum Hall nematic transition , 2013, 1303.3041.

[24]  K. West,et al.  Evidence for a ν=5/2 fractional quantum Hall nematic state in parallel magnetic fields , 2013, 1302.6304.

[25]  M. Shayegan,et al.  Composite fermions with tunable Fermi contour anisotropy. , 2013, Physical review letters.

[26]  Fu-Chun Zhang,et al.  Fractional quantum Hall states in two-dimensional electron systems with anisotropic interactions , 2012, 1203.1982.

[27]  Bohm-Jung Yang,et al.  Band mass anisotropy and the intrinsic metric of fractional quantum Hall systems , 2012, 1202.5586.

[28]  K. West,et al.  Evidence for a fractionally quantized Hall state with anisotropic longitudinal transport , 2011, 1109.3219.

[29]  F. Haldane.  Geometrical description of the fractional quantum Hall effect. , 2011, Physical review letters.

[30]  C. Nayak,et al.  Effective Field Theory of Fractional Quantized Hall Nematics , 2011, 1104.0256.

[31]  T. Gokmen,et al.  Transference of transport anisotropy to composite fermions , 2010, 1009.5732.

[32]  T. Gokmen,et al.  Contrast between spin and valley degrees of freedom , 2010, 1008.2536.

[33]  K. West,et al.  Effect of strain on stripe phases in the quantum Hall regime. , 2010, Physical review letters.

[34]  S. Sondhi,et al.  Nematic valley ordering in quantum Hall systems , 2010, 1003.1978.

[35]  Michael J. Lawler,et al.  Nematic Fermi Fluids in Condensed Matter Physics , 2009, 0910.4166.

[36]  T. Gokmen,et al.  Density dependence of valley polarization energy for composite fermions , 2009, 0907.0508.

[37]  S. Simon,et al.  Non-Abelian Anyons and Topological Quantum Computation , 2007, 0707.1889.

[38]  M. Shayegan,et al.  Valley polarization and susceptibility of composite fermions around a filling factor nu=3/2. , 2007, Physical review letters.

[39]  S. Simon,et al.  Impact of spin-orbit coupling on quantum Hall nematic phases. , 2007, Physical review letters.

[40]  O. Gunawan,et al.  Two‐dimensional electrons occupying multiple valleys in AlAs , 2006, cond-mat/0606158.

[41]  O. Gunawan,et al.  Valley susceptibility of an interacting two-dimensional electron system. , 2006, Physical review letters.

[42]  M. Shayegan,et al.  Spin susceptibility of two-dimensional electrons in narrow AlAs quantum wells. , 2004, Physical review letters.

[43]  M. Shayegan,et al.  Low-temperature, in situ tunable, uniaxial stress measurements in semiconductors using a piezoelectric actuator , 2003, cond-mat/0411740.

[44]  R. Winkler.  Spin-orbit Coupling Effects in Two-Dimensional Electron and Hole Systems , 2003 .

[45]  M. Shayegan,et al.  Enhanced electron mobility and high order fractional quantum Hall states in AlAs quantum wells , 2002 .

[46]  K. West,et al.  Insulating and fractional quantum hall states in the first excited Landau level. , 2001, Physical review letters.

[47]  Haldane,et al.  Incompressible paired hall state, stripe order, and the composite fermion liquid phase in half-filled landau levels , 1999, Physical review letters.

[48]  K. Nho,et al.  Nematic phase of the two-dimensional electron gas in a magnetic field , 1999, Physical review letters.

[49]  S. Girvin,et al.  Field-tilt Anisotropy Energy in Quantum Hall Stripe States , 1999, cond-mat/9905353.

[50]  H. Manoharan,et al.  Anisotropic transport of two-dimensional holes in high Landau levels , 1999, cond-mat/9903405.

[51]  L. Pfeiffer,et al.  Anisotropic States of Two-Dimensional Electron Systems in High Landau Levels: Effect of an In-Plane Magnetic Field , 1999, cond-mat/9903196.

[52]  K. West,et al.  Strongly Anisotropic Electronic Transport at Landau Level Filling Factor [nu] =9/2 and [nu] =5/2 under a Tilted Magnetic Field , 1999, cond-mat/9903160.

[53]  K. West,et al.  Strongly Anisotropic Transport in Higher Two-Dimensional Landau Levels , 1998, cond-mat/9812025.

[54]  E. Fradkin,et al.  Liquid-crystal phases of quantum hall systems , 1998, cond-mat/9810151.

[55]  L. Pfeiffer,et al.  Reply to Simon's Comment on "Evidence for an Anisotropic State of Two-Dimensional Electrons in High Landau Levels" , 1998, cond-mat/9903153.

[56]  R. Moessner,et al.  Exact results for interacting electrons in high Landau levels. , 1996, Physical review. B, Condensed matter.

[57]  B. Shklovskii,et al.  Ground state of a two-dimensional electron liquid in a weak magnetic field. , 1996, Physical review. B, Condensed matter.

[58]  B. Shklovskii,et al.  Charge density wave in two-dimensional electron liquid in weak magnetic field. , 1995, Physical review letters.

[59]  M. Shayegan,et al.  Wigner crystal versus Hall insulator. , 1994, Physical review. B, Condensed matter.

[60]  Wilczek,et al.  Paired Hall states in double-layer electron systems. , 1992, Physical review. B, Condensed matter.

[61]  Santos,et al.  Observation of a nu =1/2 fractional quantum Hall state in a double-layer electron system. , 1992, Physical review letters.

[62]  Gregory W. Moore,et al.  Nonabelions in the fractional quantum Hall effect , 1991 .

[63]  Tsui,et al.  Collapse of the even-denominator fractional quantum Hall effect in tilted fields. , 1988, Physical review letters.

[64]  Tsui,et al.  Observation of an even-denominator quantum number in the fractional quantum Hall effect. , 1987, Physical review letters.