VOLUME 48, NUMBER 22 PHYSICAL REVIEW LETTERS 31MAy1982 Two-Dimensional Magnetotransport in the Extreme Quantum Limit D. C. Tsui, (a), (b) H. L. Stormer, () and A. C. Gossard Bell Laboratories, Murray Hill, New Jersey 07974 (Received 5 March 1982) A quantized Hall plateau of pxy hle, accompanied by a minimum in, was observed charge-density-wave state with triangular symmetry is suggested as a possible explana- tion. PACS numbers:72.20.my,71.45.-d,73.40.lq,73.60.w In the presence of an intense perpendicular shows a dip at v=s, which becomes stronger at magnetic field B, system of two-dimensional lower T. For< Pxx follows an approximately (2D)electrons is expected to form a Wigner sol-exponential increase with inverse T. The Hall id12 at low temperatures (T). In the infinite-B resistivity Pxy on the other hand, approaches a limit, an analogy can be drawn to the classical electron gas on the su step of 3h at as rdecreases, but re- which crystallizes int ratio of this Hall plateau. These features of the data re- the electron's average pot to thermal semble those of the quantized Hall resistance and energy r=e2m1//ekT=13 the zero-resistance state expected exclusively for areal density). At fini fects be- integral values of v. We suggest that these strik- harge-density-wave ing results are evidence for a new electronic consistent with the no- sible at conside or a CDW state with Wigner crystallizati etry, is favored at v=s carried out on the S when the unit cell area of the lattice is multi- Sio2 interface. Kawa he area of a magnetic flux quantum. Tsui6 made high-B ments and observ consisting of 1-um undoped GaAs, 600-A Si-doped , dependences whic Si-doped GaAs single dependent-electron ly grown on insulating Subsequently, Kenn using molecular-beam-epitaxy cyclotron resonanc on gas, resulting from line narrowing, ide AlGaAs, 2is average electro aAs side of the GaAs- ron diameter. oles were cut into the dependence es and Ohmic contacts to the level filling fact e made with In at 400C. Low- pinned-CDW mo s were used to deter- account of the cye amples have from 1.1 10 in the range of n a rom8000to100000 performed, local The high-B measurements were per- SiO2 interface is formed at the Francis Bitter National Magnet the absence b en as peen possible t Figure shows p xy and xx of one specimen as f rom t te p e ra t ures. In this Letter he scale at the top of the figure shows the Lan- results on the tra dau level filling factor v, which gives the number electrons, in GaA of occupied levels. At integral values of v, the the extreme quantum limit (<1), when the low data sho haracteristic feature €9Un-€- est-energy, spin-polarized Landau level is par tized Hall plateaus and the vanishing of pxx, 13-15 tially filled. We found that at temperatures T<5 when the Fermi energy is pinned in the gap K, the diagonal part xx of the resistivity tensor between two adjacent levels. Removal of spin de- 1982 The American Physical Society 1559