Switching of a Magnet by Spin-Orbit Torque from a Topological Dirac Semimetal.

Recent experiments show that topological surface states (TSS) in topological insulators (TI) can be exploited to manipulate magnetic ordering in ferromagnets. In principle, TSS should also exist for other topological materials, but it remains unexplored as to whether such states can also be utilized to manipulate ferromagnets. Herein, current-induced magnetization switching enabled by TSS in a non-TI topological material, namely, a topological Dirac semimetal α-Sn, is reported.

Topological Hall Effect in a Topological Insulator Interfaced with a Magnetic Insulator.

A topological insulator (TI) interfaced with a magnetic insulator (MI) may host an anomalous Hall effect (AHE), a quantum AHE, and a topological Hall effect (THE). Recent studies, however, suggest that coexisting magnetic phases in TI/MI heterostructures may result in an AHE-associated response that resembles a THE but in fact is not. This Letter reports a genuine THE in a TI/MI structure that has only one magnetic phase.

Magnetization switching using topological surface states.

Topological surface states (TSSs) in a topological insulator are expected to be able to produce a spin-orbit torque that can switch a neighboring ferromagnet. This effect may be absent if the ferromagnet is conductive because it can completely suppress the TSSs, but it should be present if the ferromagnet is insulating. This study reports TSS-induced switching in a bilayer consisting of a topological insulator BiSe and an insulating ferromagnet BaFeO.

Spin-orbit torque-assisted switching in magnetic insulator thin films with perpendicular magnetic anisotropy.

As an in-plane charge current flows in a heavy metal film with spin-orbit coupling, it produces a torque on and thereby switches the magnetization in a neighbouring ferromagnetic metal film. Such spin-orbit torque (SOT)-induced switching has been studied extensively in recent years and has shown higher efficiency than switching using conventional spin-transfer torque. Here we report the SOT-assisted switching in heavy metal/magnetic insulator systems.

Chaotic dynamics of driven flux drops: a superconducting "dripping faucet".

When a current is applied to a type-I superconducting strip containing a narrow channel across its width, magnetic flux spots nucleate at the edge and are then driven along the channel by the current. These flux "drops" are reminiscent of water drops dripping from a faucet, a model system for studying low-dimensional chaos. We use a novel high-bandwidth Hall probe to detect in real time the motion of individual flux spots moving along the channel.

Critical field for complete vortex expulsion from narrow superconducting strips.

We have measured the maximum field for which vortices are completely expelled from a thin-film superconducting strip. Niobium strips of width W were field cooled and imaged with a scanning Hall-probe microscope. Below a critical field B(m) approximately Phi(0)/W(2) all flux was expelled; above this field vortices were observed with a density increasing approximately linearly with field.

Vortex configurations, matching, and domain structure in large arrays of artificial pinning centers.

High-resolution scanning Hall probe microscopy has been used to image vortex configurations in very large periodic arrays of artificial pinning sites. Strong matching effects are seen at fields where either one or two vortices can sit at a site; with three vortices per site, however, no clear matching is observed. Matching effects have also been observed at several fractional multiples of the matching field, including 1/5, 1/4, 1/3, 1/2, and 3/4.

Radiotherapy with or without hyperthermia in the treatment of superficial localized breast cancer: results from five randomized controlled trials. International Collaborative Hyperthermia Group.

Purpose: Claims for the value of hyperthermia as an adjunct to radiotherapy in the treatment of cancer have mostly been based on small Phase I or II trials. To test the benefit of this form of treatment, randomized Phase III trials were needed.

Methods And Materials: Five randomized trials addressing this question were started between 1988 and 1991.

Effect of vasoactive drugs on tumour blood flow as determined by 2H nuclear magnetic resonance spectroscopy.

A selective reduction in tumour blood flow (TBF) could enhance the effects of hyperthermia treatment and of drugs toxic to hypoxic cells. Vasodilator-induced changes in TBF were monitored in transplanted rat fibrosarcomas by non-invasively measuring the uptake of D2O using 2H nuclear magnetic resonance spectroscopy. Hydralazine (1 or 5 mg kg-1) caused a large (45%) reduction in mean arterial blood pressure (MABP) and a 40-60% reduction in TBF.

From hydralazine to CGRP to man?

Attempts to selectively reduce tumour blood flow have, in the past, concentrated on the use of hydralazine. However, although this vasodilator can be highly effective in experimental animals, it is only at such high concentration as to result in a severe and clinically unacceptable reduction in systemic blood pressure. At clinically acceptable levels, the drug appears to produce a small increase in tumour blood flow.

The potential for prazosin and calcitonin gene-related peptide (CGRP) in causing hypoxia in tumours.

Using 31P NMR spectroscopy, changes in tumour metabolic status were studied in a transplanted rat fibrosarcoma following the administration of vasodilators. Mean Arterial Blood Pressure (MABP) was monitored simultaneously. Two vasodilators were studied, prazosin and CGRP, which altered the NMR parameters Pi/sigma P, beta NTP,Pi, PCr/Pi and PME/Pi in a dose dependent manner.

Differences in vascular response between primary and transplanted tumours.

The vast majority of studies on tumour vasculature are performed on transplanted tumours in rodents. However, it is known that there may be differences between primary and transplanted lesions. The purpose of this study is to test whether a specific vascular response is similar in primary tumours and in transplanted tumours derived from them.

Treatment of menorrhagia by radiofrequency heating.

A new technique is described for the treatment of menorrhagia by heating the whole of the endometrial cavity of the uterus. A capacitively coupled probe at 27.12 MHz is inserted into the uterine cavity, which causes the basilis layer to be raised to approximately 50-55 degrees C whilst the rest of the pelvic contents remain at approximately normal (body) temperature.

The energy metabolism of RIF-1 tumours following hydralazine.

Phosphorus-31 Magnetic Resonance Spectroscopy (MRS) was used to observe the effect of two doses of the vasodilator hydralazine on the energy status of RIF-1 tumours. An intravenous dose of 5 mg/kg hydralazine reduced the high energy phosphate metabolites PCr and ATP, lowered pHMRS and raised the levels of inorganic phosphate of tumours within 20 min of administering the drug. The levels of high energy metabolites continued to decrease for at least 24 h.

The combined measurement of blood flow and metabolism in RIF-1 tumours in vivo. A study using H2 flow and 31P NMR spectroscopy.

Blood flow and phosphorus metabolites have been measured simultaneously in the murine RIF-1 tumour in vivo. Blood flow was measured using the H2 washout technique and 31P NMR spectroscopy was used to measure high energy phosphates, inorganic phosphate and intracellular pH within the tumour. Following NMR and flow measurements, hydralazine was administered and the measurements repeated.

Treatment of functional menorrhagia by radiofrequency-induced thermal endometrial ablation.

42 patients were enrolled in a trial of radiofrequency-induced thermal endometrial ablation for the treatment of functional menorrhagia. The radiofrequency electromagnetic energy was delivered via a probe placed within the endometrial cavity. 10 patients received 330 kJ of energy, 10 received 445 kJ, and the other 22 received 660 kJ.

Expression of dose in neutron therapy.

A pragmatic approach in neutron dosimetry is to consider the energy spectrum to consist of a neutron and a gamma component. The relationship between the two components of dose in neutron radiotherapy has been investigated for energies currently in clinical use. Changes in the neutron component itself are not dealt with.