The quantized version of the anomalous Hall effect has been predicted to occur in magnetic topological insulators, but the experimental realization has been challenging. Here, we report the observation of the quantum anomalous Hall (QAH) effect in thin films of chromium-doped (Bi,Sb)2Te3, a magnetic topological insulator. At zero magnetic field, the gate-tuned anomalous Hall resistance reaches the predicted quantized value of h/e(2), accompanied by a considerable drop in the longitudinal resistance. Under a strong magnetic field, the longitudinal resistance vanishes, whereas the Hall resistance remains at the quantized value. The realization of the QAH effect may lead to the development of low-power-consumption electronics.

Homo naledi is a previously-unknown species of extinct hominin discovered within the Dinaledi Chamber of the Rising Star cave system, Cradle of Humankind, South Africa. This species is characterized by body mass and stature similar to small-bodied human populations but a small endocranial volume similar to australopiths. Cranial morphology of H. naledi is unique, but most similar to early Homo species including Homo erectus, Homo habilis or Homo rudolfensis. While primitive, the dentition is generally small and simple in occlusal morphology. H. naledi has humanlike manipulatory adaptations of the hand and wrist. It also exhibits a humanlike foot and lower limb. These humanlike aspects are contrasted in the postcrania with a more primitive or australopith-like trunk, shoulder, pelvis and proximal femur. Representing at least 15 individuals with most skeletal elements repeated multiple times, this is the largest assemblage of a single species of hominins yet discovered in Africa.

In addition to the weak antilocalization cusp observed in the magnetoresistance (MR) Thin films of Bi 2 Te 2 Se were grown on Si (111) at 200 °C using MBE. The base pressure in the MBE chamber was ~ 7×10 -10 torr prior to the growth. Flux monitors in the MBE system allow the evaporated thickness to be monitored in real time during the growth. 14 The stochiometry was calibrated prior to the growth and monitored during the growth to achieve a 2:2:1 ratio of Bi:Te:Se. This ratio was later confirmed by energy dispersive X-ray spectrometry. X-ray diffraction data showed good c-axis alignment for all films, having (000ℓ)diffractionpeaksuptoℓ=21asshownin Fig. 1. We confirmed the formation of a single phase and found no evidence of peak splitting. The inset of Fig. 1 shows the (0006) reflection peak with Kiessig fringes in the vicinity of the Bragg peak corresponding to the 15 nm thickness of the film. Magnetotransport measurements were performed on photolithography-patterned Hall bars (1 mm long and 0.3 mm wide). The samples were measured at temperatures down to T = 7 K and in magnetic fields up to B = 14 T. The Hall voltage was found to be linear in field and the electron density was ~ 5×10 19 cm -3 .

This paper describes the 108 femoral, patellar, tibial, and fibular elements of a new species of Homo (Homo naledi) discovered in the Dinaledi chamber of the Rising Star cave system in South Africa. Homo naledi possesses a mosaic of primitive, derived, and unique traits functionally indicative of a bipedal hominin adapted for long distance walking and possibly running. Traits shared with australopiths include an anteroposteriorly compressed femoral neck, a mediolaterally compressed tibia, and a relatively circular fibular neck. Traits shared with Homo include a well-marked linea aspera, anteroposteriorly thick patellae, relatively long tibiae, and gracile fibulae with laterally oriented lateral malleoli. Unique features include the presence of two pillars on the superior aspect of the femoral neck and a tubercular distal insertion of the pes anserinus on the tibia. The mosaic morphology of the H. naledi thigh and leg appears most consistent with a species intermediate between Australopithecus spp. and Homo erectus and, accordingly, may offer insight into the nature of the earliest members of genus Homo. These fossils also expand the morphological diversity of the Homo lower limb, perhaps indicative of locomotor diversity in our genus.