A topological p-n junction (TPNJ) is an important concept to control spin and charge transport on a surface of three-dimensional topological insulators (3D-TIs). Here we report successful fabrication of such TPNJ on a surface of 3D-TI Bi2−xSbxTe3−ySey thin films and experimental observation of the electrical transport. By tuning the chemical potential of n-type topological Dirac surface of Bi2−xSbxTe3−ySey on its top half by using tetrafluoro-7,7,8,8-tetracyanoquinodimethane as an organic acceptor molecule, a half surface can be converted to p-type with leaving the other half side as the opposite n-type, and consequently TPNJ can be created. By sweeping the back-gate voltage in the field effect transistor structure, the TPNJ was controlled both on the bottom and the top surfaces. A dramatic change in electrical transport observed at the TPNJ on 3D-TI thin films promises novel spin and charge transport of 3D-TIs for future spintronics.
The interplay of magnetism and spin-orbit coupling on an Fe kagome lattice in Fe
3
Sn
2
crystal produces a unique band structure leading to an order of magnitude larger anomalous Hall effect than in conventional ferromagnetic metals. In this work, we demonstrate that Fe-Sn nanocrystalline films also exhibit a large anomalous Hall effect, being applicable to magnetic sensors that satisfy both high sensitivity and thermal stability. In the films prepared by a co-sputtering technique at room temperature, the partial development of crystalline lattice order appears as nanocrystals of the Fe-Sn kagome layer. The tangent of Hall angle, the ratio of Hall resistivity to longitudinal resistivity, is maximized in the optimal alloy composition of close to Fe
3
Sn
2
, implying the possible contribution of the kagome origin even though the films are composed of nanocrystal and amorphous-like domains. These ferromagnetic Fe-Sn films possess great advantages as a Hall sensor over semiconductors in thermal stability owing to the weak temperature dependence of the anomalous Hall responses. Moreover, the room-temperature fabrication enables us to develop a mechanically flexible Hall sensor on an organic substrate. These demonstrations manifest the potential of ferromagnetic kagome metals as untapped reservoir for designing new functional devices.
Objectives
To investigate how much minimal residual membranous urethral length (mRUL) and maximal urethral length (MUL) measured on MRI preoperatively affect postoperative urinary incontinence (PUI) and recovery in robot‐assisted radical prostatectomy (RARP) and open radical prostatectomy (ORP).
Methods
The subjects were 190 and 110 patients undergoing RARP and ORP, respectively, in our institution. Patients underwent preoperative MRI for prostate cancer evaluation and completed the quality of life questionnaire of the Expanded Prostate Cancer Index Composite instrument before and 1, 3, 6, and 12 months after surgery. The parameters of mRUL and MUL were measured on MRI and analyzed along with other parameters including age, body mass index, and nerve sparing.
Results
The median mRUL and MUL were 7.81 and 14.27 mm in the RARP group and 7.15 and 13.57 mm in the ORP group, respectively. Recovery rates from PUI were similar in the two groups. Multivariate analyses showed that mRUL was a predictor of baseline continence, whereas shorter MUL was a predictor of poor recovery from PUI. Patients with both shorter mRUL and MUL had significantly worse recoveries from PUI after RARP and ORP than patients with longer mRUL and MUL.
Conclusions
Minimal residual membranous urethral length contributes to urethral function as basal urinary continence, whereas MUL represents the potential of recovery from PUI in RARP and ORP. The MUL measured by preoperative MRI can predict poor recovery from PUI after radical prostatectomy and combined evaluation of MUL and mRUL support to anticipate poor recovery of PUI.
We report on the electronic states and the transport properties of three-dimensional topological insulator (Bi<sub>1-<i>x</i></sub>Sb<sub><i>x</i></sub>)<sub>2</sub>Se<sub>3</sub> ternary alloy thin films grown on an isostructural Bi<sub>2</sub>Se<sub>3</sub> buffer layer on InP substrates. By angle-resolved photoemission spectroscopy, we clearly detected Dirac surface states with a large bulk band gap of 0.2 - 0.3 eV in the (Bi<sub>1-<i>x</i></sub>Sb<sub><i>x</i></sub>)<sub>2</sub>Se<sub>3</sub> film with <i>x</i> = 0.70. In addition, we observed by Hall effect measurements that the dominant charge carrier converts from electron (n-type) to hole (p-type) at around <i>x</i> = 0.7, indicating that the Fermi level can be controlled across the Dirac point. Indeed, the carrier transport was shown to be governed by Dirac surface state in 0.63 ≤ <i>x</i> ≤ 0.75.These features suggest that Fermi-level tunable (Bi<sub>1-<i>x</i></sub>Sb<sub><i>x</i></sub>)<sub>2</sub>Se<sub>3</sub>-based heterostructures provide a platform for extracting exotic topological phenomena.
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