Valence band energy spectrum of HgTe quantum wells with an inverted band structure

Valence band energy spectrum of HgTe quantum wells with an inverted band structure The energy spectrum of the valence band in HgTe/CdxHg1−xTe quantum wells of a width (8–20) nm has been studied experimentally by magnetotransport effects and theoretically in the framework of a four-band kP method. Comparison of the Hall density with the density found from a period of the Shubnikov–de Haas (SdH) oscillations clearly shows that the degeneracy of states of the top of the valence band is equal to 2 at the hole density p<5.5×1011cm−2. Such degeneracy does not agree with the calculations of the spectrum performed within the framework of the four-band kP method for symmetric quantum wells. These calculations show that the top of the valence band consists of four spin-degenerate extremes located at k≠0 (valleys) which gives the total degeneracy K=8. It is shown that taking into account the “mixing of states” at the interfaces leads to the removal of the spin degeneracy that reduces the degeneracy to K=4. Accounting for any additional asymmetry, for example, due to the difference in the mixing parameters at the interfaces, the different broadening of the boundaries of the well, etc., leads to reduction of the valleys degeneracy, making K=2. It is noteworthy that for our case twofold degeneracy occurs due to degeneracy of two single-spin valleys. The hole effective mass (mh) determined from analysis of the temperature dependence of the amplitude of the SdH oscillations shows that mh is equal to (0.25±0.02)m0 and weakly increases with the hole density. Such a value of mh and its dependence on the hole density are in a good agreement with the calculated effective mass. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Physical Review B American Physical Society (APS)

Valence band energy spectrum of HgTe quantum wells with an inverted band structure

Preview Only

Valence band energy spectrum of HgTe quantum wells with an inverted band structure

Abstract

The energy spectrum of the valence band in HgTe/CdxHg1−xTe quantum wells of a width (8–20) nm has been studied experimentally by magnetotransport effects and theoretically in the framework of a four-band kP method. Comparison of the Hall density with the density found from a period of the Shubnikov–de Haas (SdH) oscillations clearly shows that the degeneracy of states of the top of the valence band is equal to 2 at the hole density p<5.5×1011cm−2. Such degeneracy does not agree with the calculations of the spectrum performed within the framework of the four-band kP method for symmetric quantum wells. These calculations show that the top of the valence band consists of four spin-degenerate extremes located at k≠0 (valleys) which gives the total degeneracy K=8. It is shown that taking into account the “mixing of states” at the interfaces leads to the removal of the spin degeneracy that reduces the degeneracy to K=4. Accounting for any additional asymmetry, for example, due to the difference in the mixing parameters at the interfaces, the different broadening of the boundaries of the well, etc., leads to reduction of the valleys degeneracy, making K=2. It is noteworthy that for our case twofold degeneracy occurs due to degeneracy of two single-spin valleys. The hole effective mass (mh) determined from analysis of the temperature dependence of the amplitude of the SdH oscillations shows that mh is equal to (0.25±0.02)m0 and weakly increases with the hole density. Such a value of mh and its dependence on the hole density are in a good agreement with the calculated effective mass.
Loading next page...
 
/lp/aps_physical/valence-band-energy-spectrum-of-hgte-quantum-wells-with-an-inverted-JmORK5P8bt
Publisher
The American Physical Society
Copyright
Copyright © ©2017 American Physical Society
ISSN
1098-0121
eISSN
1550-235X
D.O.I.
10.1103/PhysRevB.96.035310
Publisher site
See Article on Publisher Site

Abstract

The energy spectrum of the valence band in HgTe/CdxHg1−xTe quantum wells of a width (8–20) nm has been studied experimentally by magnetotransport effects and theoretically in the framework of a four-band kP method. Comparison of the Hall density with the density found from a period of the Shubnikov–de Haas (SdH) oscillations clearly shows that the degeneracy of states of the top of the valence band is equal to 2 at the hole density p<5.5×1011cm−2. Such degeneracy does not agree with the calculations of the spectrum performed within the framework of the four-band kP method for symmetric quantum wells. These calculations show that the top of the valence band consists of four spin-degenerate extremes located at k≠0 (valleys) which gives the total degeneracy K=8. It is shown that taking into account the “mixing of states” at the interfaces leads to the removal of the spin degeneracy that reduces the degeneracy to K=4. Accounting for any additional asymmetry, for example, due to the difference in the mixing parameters at the interfaces, the different broadening of the boundaries of the well, etc., leads to reduction of the valleys degeneracy, making K=2. It is noteworthy that for our case twofold degeneracy occurs due to degeneracy of two single-spin valleys. The hole effective mass (mh) determined from analysis of the temperature dependence of the amplitude of the SdH oscillations shows that mh is equal to (0.25±0.02)m0 and weakly increases with the hole density. Such a value of mh and its dependence on the hole density are in a good agreement with the calculated effective mass.

Journal

Physical Review BAmerican Physical Society (APS)

Published: Jul 26, 2017

There are no references for this article.

Sorry, we don’t have permission to share this article on DeepDyve,
but here are related articles that you can start reading right now:

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off