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Composite fermions with a valley deg...

Padmanabhan, Medini.

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Composite fermions with a valley degree of freedom.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Composite fermions with a valley degree of freedom./
作者:	Padmanabhan, Medini.
面頁冊數:	130 p.
附註:	Source: Dissertation Abstracts International, Volume: 71-04, Section: B, page: 2449.
Contained By:	Dissertation Abstracts International71-04B.
標題:	Engineering, Electronics and Electrical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3401583
ISBN:	9781109688429

Composite fermions with a valley degree of freedom.
Padmanabhan, Medini.

Composite fermions with a valley degree of freedom. - 130 p.

Source: Dissertation Abstracts International, Volume: 71-04, Section: B, page: 2449.

Thesis (Ph.D.)--Princeton University, 2010.

This thesis explores the Physics of the fractional quantum Hall (FQH) effect in two-dimensional electron systems confined to AlAs quantum wells. In addition to spin, these electrons also posses a valley degree of freedom which raises the exciting possibility of a transfer of this characteristic to the composite fermions (CFs). We experimentally tune the valley occupation in our system via the application of strain.

ISBN: 9781109688429Subjects--Topical Terms:

626636
Engineering, Electronics and Electrical.

Composite fermions with a valley degree of freedom.
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245 1 0 $a Composite fermions with a valley degree of freedom.
300 $a 130 p.
500 $a Source: Dissertation Abstracts International, Volume: 71-04, Section: B, page: 2449.
500 $a Adviser: Mansour Shayegan.
502 $a Thesis (Ph.D.)--Princeton University, 2010.
520 $a This thesis explores the Physics of the fractional quantum Hall (FQH) effect in two-dimensional electron systems confined to AlAs quantum wells. In addition to spin, these electrons also posses a valley degree of freedom which raises the exciting possibility of a transfer of this characteristic to the composite fermions (CFs). We experimentally tune the valley occupation in our system via the application of strain.
520 $a We find that the CFs formed around the Landau level filling factor nu = 3/2 are fully spin polarized but possess a valley degree of freedom of their own. The response of the various FQH states around nu = 3/2 to strain is captured by a CF Landau level fan diagram drawn for a single-spin, two-valley system. We measure the energy needed to completely valley polarize these CFs. We repeat this measurement for CFs around nu = 1/2 which are the particle-hole conjugates of the CFs formed around nu = 3/2. While we observe that the CFs around nu = 1/2 also have a valley degree of freedom, their valley polarization energies are smaller by up to a factor of four than those of their counterparts around nu = 3/2. This discrepancy shows a particle-hole symmetry breaking in our system. Interestingly, the theory developed for single-valley, two-spin systems agrees better with the results around nu = 3/2.
520 $a We also report the observation of persistent FQH states at nu = 1/3 and 5/3 at zero strain when the two valleys are degenerate. In the CF picture these FQH states are analogous to the integer quantum Hall state at nu = 1, which is known to form a quantum Hall ferromagnet in the limit of zero valley splitting. We compare the energy gaps measured at nu = 1/3 and 5/3 to the theory developed for single-valley, two-spin systems and find that the gaps and their rates of rise with strain are much smaller than predicted.
590 $a School code: 0181.
650 4 $a Engineering, Electronics and Electrical. $3 626636
650 4 $a Physics, Low Temperature. $3 1669075
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791 $a Ph.D.
792 $a 2010
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