ABSTRACT
The topological Hall effect is used extensively to study chiral spin textures in various materials. However, the factors controlling its magnitude in technologically-relevant thin films remain uncertain. Using variable-temperature magnetotransport and real-space magnetic imaging in a series of Ir/Fe/Co/Pt heterostructures, here we report that the chiral spin fluctuations at the phase boundary between isolated skyrmions and a disordered skyrmion lattice result in a power-law enhancement of the topological Hall resistivity by up to three orders of magnitude. Our work reveals the dominant role of skyrmion stability and configuration in determining the magnitude of the topological Hall effect.
ABSTRACT
We report experimental coupling of chiral magnetism and superconductivity in [IrFeCoPt]/Nb heterostructures. The stray field of skyrmions with radius ≈50 nm is sufficient to nucleate antivortices in a 25 nm Nb film, with unique signatures in the magnetization, critical current, and flux dynamics, corroborated via simulations. We also detect a thermally tunable Rashba-Edelstein exchange coupling in the isolated skyrmion phase. This realization of a strongly interacting skyrmion-(anti)vortex system opens a path toward controllable topological hybrid materials, unattainable to date.
ABSTRACT
Previous studies have suggested elevated estrogen production in tumour-bearing breast quadrants as well as in breast cancers versus benign tissue. Using highly sensitive assays, we determined breast cancer tissue estrogen concentrations together with plasma and benign tissue estrogen concentrations in each quadrant obtained from mastectomy specimens (34 postmenopausal and 13 premenopausal women). We detected similar concentrations of each of the three major estrogens estradiol (E(2)), estrone (E(1)) and E(1)S in tumour-bearing versus non-tumour-bearing quadrants. Considering malignant tumours, intratumour E(1) levels were reduced in cancer tissue obtained from pre- as well as postmenopausal women independent of tumour ER status (average ratio E(1) cancer: benign tissue of 0.2 and 0.3, respectively; p<0.001 for both groups), suggesting intratumour aromatization to be of minor importance. The most striking finding was a significant (4.1-8.6-fold) increased E(2) concentration in ER positive tumours versus normal tissue (p<0.05 and <0.001 for pre- and postmenopausal patients, respectively), contrasting low E(2) concentrations in ER- tumours (p<0.01 and <0.001 comparing E(2) levels between ER+ and ER- tumours in pre- and postmenopausals, respectively). A possible explanation to our finding is increased ligand receptor binding capacity for E(2) in receptor positive tumours but alternative factors influencing intratumour estrogen disposition cannot be excluded.
