arXiv subjects

Tao Hou

Publications and source records attributed to Tao Hou.

40 records · Page 3Linked to original sources

arXiv2019

Pressure-Induced Modification of Anomalous Hall Effect in Layered Fe$_3$GeTe$_2$

We systematically investigate the influence of high pressure on the electronic transport properties of layered ferromagnetic materials, in particular, those of Fe$_3$GeTe$_2$. Its crystal sustains a hexagonal phase under high pressures up to 25.9 GPa, while the Curie temperature decreases monotonously with the increasing pressure. By applying appropriate pressures, the experimentally measured anomalous Hall conductivity, $σ_{xy}^A$, can be efficiently controlled. Our theoretical study reveals that this finding can be attributed to the shift of the spin--orbit-coupling-induced splitting bands of Fe atoms. With loading compression, $σ_{xy}^A$ reaches its maximal value when the Fermi level lies inside the splitting bands and then attenuates when the splitting bands float above the Fermi level. Further compression leads to a prominent suppression of the magnetic moment, which is another physical cause of the decrease in $σ_{xy}^A$ at high pressure. These results indicate that the application of pressure is an effective approach in controlling the anomalous Hall conductivity of layered magnetic materials, which elucidates the physical mechanism of the large intrinsic anomalous Hall effect.

cond-mat.mtrl-sci↗

arXiv2018

Persistent 1-Cycles: Definition, Computation, and Its Application

Persistence diagrams, which summarize the birth and death of homological features extracted from data, are employed as stable signatures for applications in image analysis and other areas. Besides simply considering the multiset of intervals included in a persistence diagram, some applications need to find representative cycles for the intervals. In this paper, we address the problem of computing these representative cycles, termed as persistent 1-cycles, for $\text{H}_1$-persistent homology with $\mathbb{Z}_2$ coefficients. The definition of persistent cycles is based on the interval module decomposition of persistence modules, which reveals the structure of persistent homology. After showing that the computation of the optimal persistent 1-cycles is NP-hard, we propose an alternative set of meaningful persistent 1-cycles that can be computed with an efficient polynomial time algorithm. We also inspect the stability issues of the optimal persistent 1-cycles and the persistent 1-cycles computed by our algorithm with the observation that the perturbations of both cannot be properly bounded. We design a software which applies our algorithm to various datasets. Experiments on 3D point clouds, mineral structures, and images show the effectiveness of our algorithm in practice.

cs.CG↗

arXiv2018

Topological Zero-Line Modes in Folded Bilayer Graphene

We theoretically investigate a folded bilayer graphene structure as an experimentally realizable platform to produce the one-dimensional topological zero-line modes. We demonstrate that the folded bilayer graphene under an external gate potential enables tunable topologically conducting channels to be formed in the folded region, and that a perpendicular magnetic field can be used to enhance the conducting when external impurities are present. We also show experimentally that our proposed folded bilayer graphene structure can be fabricated in a controllable manner. Our proposed system greatly simplifies the technical difficulty in the original proposal by considering a planar bilayer graphene (i.e., precisely manipulating the alignment between vertical and lateral gates on bilayer graphene), laying out a new strategy in designing practical low-power electronics by utilizing the gate induced topological conducting channels.

cond-mat.mes-hall↗

arXiv2018

Enhanced Robustness of Zero-line Modes in Graphene via a Magnetic Field

Motivated by recent experimental results for zero-line modes (ZLMs) in a bilayer graphene system [Nature Nanotechnol. 11, 1060 (2016)], we systematically studied the influence of a magnetic field on ZLMs and demonstrated the physical origin of the enhanced robustness by employing nonequilibrium Green's functions and the Landauer-Buttiker formula. We found that a perpendicular magnetic field can separate the wavefunctions of the counter-propagating kink states into opposite directions. Specifically, the separation vanishes at the charge neutrality point. The separation increases as the Fermi level deviates from the charge neutrality point and can reach a magnitude comparable to the wavefunction spread at a moderate field strength. Such spatial separation of oppositely propagating ZLMs effectively suppresses backscattering. Moreover, the presence of a magnetic field enlarges the bulk gap and suppresses the bound states, thereby further reducing the scattering. These mechanisms effectively increase the mean free paths of the ZLMs to approximately 1 micron in the presence of a disorder.

cond-mat.mes-hall↗