Valley Stoner instability of the composite Fermi sea
We study two-component electrons in the lowest Landau level at total filling factor ν[subscript T] = 1/2 with anisotropic mass tensors and principal axes rotated by π/2 as realized in aluminum arsenide (AlAs) quantum wells. Combining exact diagonalization and the density matrix renormalization group...
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| Format: | Article |
| Language: | English |
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American Physical Society
2018
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| Online Access: | http://hdl.handle.net/1721.1/118774 https://orcid.org/0000-0002-8803-1017 |
| _version_ | 1826204708611555328 |
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| author | Zhu, Zheng Sheng, D. N. Fu, Liang Sodemann, Inti |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Zhu, Zheng Sheng, D. N. Fu, Liang Sodemann, Inti |
| author_sort | Zhu, Zheng |
| collection | MIT |
| description | We study two-component electrons in the lowest Landau level at total filling factor ν[subscript T] = 1/2 with anisotropic mass tensors and principal axes rotated by π/2 as realized in aluminum arsenide (AlAs) quantum wells. Combining exact diagonalization and the density matrix renormalization group we demonstrate that the system undergoes a quantum phase transition from a gapless state in which both flavors are equally populated to another gapless state in which all the electrons spontaneously polarize into a single flavor beyond a critical mass anisotropy of m[subscript x]/m[subscript y]∼7. We propose that this phase transition is a form of itinerant Stoner transition between a two-component and a single-component composite Fermi sea states and describe a set of trial wave functions which successfully capture the quantum numbers and shell filling effects in finite size systems as well as providing a physical picture for the energetics of these states. Our estimates indicate that the composite Fermi sea of AlAs is the analog of an itinerant Stoner magnet with a finite spontaneous valley polarization. We pinpoint experimental evidence indicating the presence of Stoner magnetism in the Jain states surrounding ν = 1/2. |
| first_indexed | 2024-09-23T12:59:47Z |
| format | Article |
| id | mit-1721.1/118774 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T12:59:47Z |
| publishDate | 2018 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/1187742022-10-01T12:24:48Z Valley Stoner instability of the composite Fermi sea Zhu, Zheng Sheng, D. N. Fu, Liang Sodemann, Inti Massachusetts Institute of Technology. Department of Physics Zhu, Zheng Fu, Liang We study two-component electrons in the lowest Landau level at total filling factor ν[subscript T] = 1/2 with anisotropic mass tensors and principal axes rotated by π/2 as realized in aluminum arsenide (AlAs) quantum wells. Combining exact diagonalization and the density matrix renormalization group we demonstrate that the system undergoes a quantum phase transition from a gapless state in which both flavors are equally populated to another gapless state in which all the electrons spontaneously polarize into a single flavor beyond a critical mass anisotropy of m[subscript x]/m[subscript y]∼7. We propose that this phase transition is a form of itinerant Stoner transition between a two-component and a single-component composite Fermi sea states and describe a set of trial wave functions which successfully capture the quantum numbers and shell filling effects in finite size systems as well as providing a physical picture for the energetics of these states. Our estimates indicate that the composite Fermi sea of AlAs is the analog of an itinerant Stoner magnet with a finite spontaneous valley polarization. We pinpoint experimental evidence indicating the presence of Stoner magnetism in the Jain states surrounding ν = 1/2. 2018-10-25T15:39:03Z 2018-10-25T15:39:03Z 2018-10 2018-03 2018-10-01T18:00:19Z Article http://purl.org/eprint/type/JournalArticle 2469-9950 2469-9969 http://hdl.handle.net/1721.1/118774 Zhu, Zheng et al. "Valley Stoner instability of the composite Fermi sea." Physical Review B 98, 15 (October 2018): 155104 © 2018 American Physical Society https://orcid.org/0000-0002-8803-1017 en http://dx.doi.org/10.1103/PhysRevB.98.155104 Physical Review B Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Physical Society application/pdf American Physical Society American Physical Society |
| spellingShingle | Zhu, Zheng Sheng, D. N. Fu, Liang Sodemann, Inti Valley Stoner instability of the composite Fermi sea |
| title | Valley Stoner instability of the composite Fermi sea |
| title_full | Valley Stoner instability of the composite Fermi sea |
| title_fullStr | Valley Stoner instability of the composite Fermi sea |
| title_full_unstemmed | Valley Stoner instability of the composite Fermi sea |
| title_short | Valley Stoner instability of the composite Fermi sea |
| title_sort | valley stoner instability of the composite fermi sea |
| url | http://hdl.handle.net/1721.1/118774 https://orcid.org/0000-0002-8803-1017 |
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