Detail Quantum Spin Hall Insulator State in HgTe Quantum Wells   Oleh:  König, Markus ; Wiedmann, Steffen ; Brüne, Christoph ; Roth, Andreas ; Buhmann, Hartmut ; Molenkamp, Laurens W. ; Xiao-Liang, Qi ; Shou-Cheng, Zhang Jenis: Article from Bulletin/Magazine Dalam koleksi: SCIENCE (keterangan: ada di Proquest) vol. 318 no. 5851 (Nov. 2007), page 766. Ketersediaan Perpustakaan FK Nomor Panggil: S01.K.2007.09 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada     Lihat Detail Induk Isi artikel Recent theory predicted that the quantum spin Hall effect, a fundamentally new quantum state of matter that exists at zero external magnetic field, may be realized in HgTe/(Hg,Cd)Te quantum wells. We fabricated such sample structures with low density and high mobility in which we could tune, through an external gate voltage, the carrier conduction from n-type to p-type, passing through an insulating regime. For thin quantum wells with well width d < 6.3 nanometers, the insulating regime showed the conventional behavior of vanishingly small conductance at low temperature. However, for thicker quantum wells (d > 6.3 nanometers), the nominally insulating regime showed a plateau of residual conductance close to 2e2/h, where e is the electron charge and h is Planck's constant. The residual conductance was independent of the sample width, indicating that it is caused by edge states. Furthermore, the residual conductance was destroyed by a small external magnetic field. The quantum phase transition at the critical thickness, d = 6.3 nanometers, was also independently determined from the magnetic field–induced insulator-to-metal transition. These observations provide experimental evidence of the quantum spin Hall effect. Opini Anda Klik untuk menuliskan opini Anda tentang koleksi ini! Kembali

Copyright © 2006, 2007 Unika Atma Jaya, all rights reserved