We show the emergence of fractional quantum Hall states in graphene grown by chemical vapor deposition (CVD) for magnetic fields from below 3 T to 35 T where the CVD-graphene was dry-transferred. Effective composite-fermion filling factors up to ν
* = 4 are visible and higher order composite-fermion states (with four flux quanta attached) start to emerge at the highest fields. Our results show that the quantum mobility of CVD-grown graphene is comparable to that of exfoliated graphene and, more specifically, that the p/3 fractional quantum Hall states have energy gaps of up to 30 K, well comparable to those observed in other silicon-gated devices based on exfoliated graphene.
High-resolution thermal-expansion measurements of single-crystalline CuO (tenorite) are reported for the temperature range 5 < T < 350 K. The data reveal three transitions (T N1 = 213 K, T N2 = 229.2 K, and T N3 = 229.8 K), which corroborate the recently proposed magnetic phase diagram [Villarreal, Quirion, Plumer, Poirier, Usui, and Kimura, Phys. Rev. Lett. 109, 167206 (2012)] revealing three distinct antiferromagnetic (AFM) phases. Analysis of the region surrounding T N2 and T N3 suggests that these phase transitions are continuous and yields estimates for the heat-capacity critical exponents of α T N2 = 0.033(2) and α T N3 = 0.040(9). Magnetic susceptibility measurements reveal spin-flop transitions at temperatures below T N1 , confirming that the b axis is the easy AFM axis.
We present inverted spin-valve devices fabricated from chemical vapor deposition (CVD)-grown bilayer graphene (BLG) that show more than a doubling in device performance at room temperature compared to state-of-the-art bilayer graphene spin valves. This is made possible by a polydimethylsiloxane droplet-assisted full-dry transfer technique that compensates for previous process drawbacks in device fabrication. Gate dependent Hanle measurements reveal spin lifetimes of up to 5.8 ns and a spin diffusion length of up to 26 μm at room temperature combined with a charge carrier mobility of about 24 000 cm 2 (V s) −1 for the best device. Our results demonstrate that CVD-grown BLG shows equally good room temperature spin transport properties as both CVD-grown single-layer graphene and even exfoliated single-layer graphene.
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