Quantum Hall effect in InAsSb quantum wells at elevated temperatures

We have characterized the electronic properties of a high-mobility two-dimensional electron system in modulation doped InAsSb quantum wells and compare them to InSb quantum wells grown in a similar fashion. Using temperature-dependent Shubnikov-de Haas experiments as well as FIR transmission, we find an effective mass of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:msup><a:mi>m</a:mi><a:mo>*</a:mo></a:msup><a:mo>≈</a:mo><a:mspace width="4pt"/><a:mn>0.022</a:mn><a:msub><a:mi>m</a:mi><a:mi>e</a:mi></a:msub></a:mrow></a:math>, which is lower than in the investigated InSb quantum well, but due to a rather strong confinement still higher than in the corresponding bulk compound. The effective <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mi>g</c:mi></c:math>-factor was determined to be <d:math xmlns:d="http://www.w3.org/1998/Math/MathML"><d:mrow><d:msup><d:mi>g</d:mi><d:mo>*</d:mo></d:msup><d:mo>≈</d:mo><d:mn>24.1</d:mn></d:mrow></d:math>. These results are also corroborated by <e:math xmlns:e="http://www.w3.org/1998/Math/MathML"><e:mrow><e:mi mathvariant="bold-italic">k</e:mi><e:mo>·</e:mo><e:mi mathvariant="bold-italic">p</e:mi></e:mrow></e:math> band structure calculations. When spin polarizing the electrons in a tilted magnetic field, the <h:math xmlns:h="http://www.w3.org/1998/Math/MathML"><h:mi>g</h:mi></h:math>-factor is significantly enhanced by electron-electron interactions, reaching a value as large as <i:math xmlns:i="http://www.w3.org/1998/Math/MathML"><i:mrow><i:msup><i:mi>g</i:mi><i:mo>*</i:mo></i:msup><i:mo>=</i:mo><i:mn>60</i:mn></i:mrow></i:math> at a spin polarization <j:math xmlns:j="http://www.w3.org/1998/Math/MathML"><j:mrow><j:mi>P</j:mi><j:mo>=</j:mo><j:mn>0.75</j:mn></j:mrow></j:math>. Finally, we show that due to the low effective mass, the quantum Hall effect in our particular sample can be observed up to a temperature of 60 K.