Metamagnetism in the 2D Hubbard Model with easy axis

Although the Hubbard model is widely investigated, there are surprisingly few attempts to study the behavior of such a model in an external magnetic field. Using the Projector Quantum Monte Carlo technique, we show that the Hubbard model with an easy axis exhibits metamagnetic behavior if an external field is turned on. For the case of intermediate correlations strength $U$, we observe a smooth transition from an antiferromagnetic regime to a paramagnetic phase. While the staggered magnetization will decrease linearly up to a critical field $B_c$, uniform magnetization develops only for fields higher than $B_c$.Comment: RevTeX 5 pages + 2 postscript figures (included), accepted for PRB Rapid Communication

Flexible Wire‐Shaped Perovskite Photodetector via Joule Heating for Improved Crystallization and Performance

Organolead triiodide perovskite (CH3NH3PbI3) is used extensively as the absorber material for both solar cells and photodetectors; however, the reported photodetectors are all planar and flexible planar devices. To the best of knowledge the first flexible wire-shaped perovskite photodetector is reported. The performance of the wire-shaped perovskite photodetector on carbon nanotube yarn (CNY) critically depends on the surface geometry and annealing conditions. The use of joule heating method for uniform control of temperature on CNY surface results in smooth perovskite crystalline films, which are used to produce self-powering photodetectors with strong responsivity (10.2 A W−1), detectivity (1.76 × 1011 J), and Ilight/Idark (45). This development displays the role of joule heating in the annealing process and demonstrates a cheap, repeatable method for the fabrication of self-powered perovskite photodetectors