Phase transitions at zero magnetic field in Si/SiGe quantum wells

AbstractThe CE phase is an extraordinary phase exhibiting the simultaneous spin, charge, and orbital ordering due to strong electron correlation. It is an ideal platform to investigate the role of the multiple orderings in the phase transitions and discover emergent properties. Here, we use a cryogenic high-field magnetic force microscope to image the phase transitions and properties of the CE phase in a Pr0.5Ca0.5MnO3 thin film. In a high magnetic field, we observed a clear suppression of magnetic susceptibility at the charge-ordering insulator transition temperature (TCOI), whereas, at the Néel temperature (TN), no significant change is observed. This observation favors the scenario of strong antiferromagnetic correlation developed below TCOI but raises questions about the Zener polaron paramagnetic phase picture. Besides, we discoverd a phase-separated surface state in the CE phase regime. Ferromagnetic phase domains residing at the surface already exist in zero magnetic field and show ultra-high magnetic anisotropy. Our results provide microscopic insights into the unconventional spin- and charge-ordering transitions and revealed essential attributes of the CE phase, highlighting unusual behaviors when multiple electronic orderings are involved.

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National High Magnetic Field Laboratory 2016 Annual Research Report: Termination of Two-Dimensional Metallic Conduction near the Metal-Insulator Transition in Si/SiGe Quantum Wells

10.2172/1505355 ◽

2016 ◽

Author(s):

Wei Pan ◽

Tzu-Ming Lu ◽

J. S. Xia ◽

N. S. Sullivan ◽

S. -H. Huang ◽

...

Keyword(s):

Magnetic Field ◽

Quantum Wells ◽

High Magnetic Field ◽

Insulator Transition ◽

Research Report ◽

Two Dimensional ◽

Metal Insulator Transition ◽

Metal Insulator ◽

Metallic Conduction ◽

Sige Quantum Wells

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ELECTRON AND HOLE EFFECTIVE g FACTORS IN InAs/GaSb QUANTUM WELLS

International Journal of Nanoscience ◽

10.1142/s0219581x0300153x ◽

2003 ◽

Vol 02 (06) ◽

pp. 437-444 ◽

Cited By ~ 1

Author(s):

A. ZAKHAROVA ◽

S. T. YEN ◽

K. A. CHAO

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Quantum Wells ◽

Landau Level ◽

Heavy Hole ◽

Strong Dependence ◽

Zero Magnetic Field ◽

Electron Level ◽

Hole Level ◽

G Factors

We investigate the Landau level structures and the electron and hole effective g factors in InAs / GaSb quantum wells under electric and quantizing magnetic fields perpendicular to interfaces. In these structures, the lowest electron level in InAs can be below the highest heavy-hole level in GaSb at zero magnetic field B. Thus the electron and hole levels anticross with the increasing magnetic field and the strong dependence of the Landau level structures as well as g factors on B is obtained. We have found that the voltage across the structure and the lattice-mismatched strain also produce the essential changes in the Landau level structures as well as the electron and hole g factors.

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