Quantum phases of electron double layers: soft collective modes and finite-temperature phase transitions

✍ Scribed by Vittorio Pellegrini; Aron Pinczuk; Brian S Dennis; Loren N Pfeiffer; Ken W West

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 96 KB
• Volume: 6
• Category: Article
• ISSN: 1386-9477
• DOI: 10.1016/s1386-9477(99)00112-5

✦ Synopsis

The extreme softening of spin excitations in electron double layers is studied by resonant inelastic light scattering. At even-integer quantum Hall states we ÿnd evidence of three distinct conÿgurations of spin. Transformations among these spin states appear as quantum phase transitions tuned by interlayer interactions and Zeeman energies. A broken-symmetry phase emerges when a long-wavelength spin excitation across the tunneling gap goes soft. Spectra measured in this phase o er remarkable evidence of ÿnite-temperature phase transitions. Critical temperatures determined from spectra display signiÿcant dependence on magnetic ÿeld.