Experimental Demonstration of a Rowland Spectrometer for Spin Waves

We experimentally demonstrate the operation of a spin-wave Rowland spectrometer. In the proposed device geometry, spin waves are coherently excited on a diffraction grating and form an interference pattern that spatially separates spectral components of the incoming signal. The diffraction grating was created by focused-ion-beam irradiation, which was found to locally eliminate the ferrimagnetic properties of YIG, without removing the material. We found that in our experiments spin waves were created by an indirect mechanism, by exploiting nonlinear resonance between the grating and the coplanar waveguide. Our work paves the way for complex spin-wave optic devices -- chips that replicate the functionality of integrated optical devices on a chip-scale.Comment: 7 pages, 5 figures, presented at Joint European Magnetic Symposia (JEMS) 202

Controlling Domain-Wall Nucleation in Ta/CoFeB/MgO Nanomagnets via Local Ga+ Ion Irradiation

Comprehensive control of the domain wall nucleation process is crucial for spin-based emerging technologies ranging from random-access and storage-class memories over domain-wall logic concepts to nanomagnetic logic. In this work, focused Ga+ ion-irradiation is investigated as an effective means to control domain-wall nucleation in Ta/CoFeB/MgO nanostructures. We show that analogously to He+ irradiation, it is not only possible to reduce the perpendicular magnetic anisotropy but also to increase it significantly, enabling new, bidirectional manipulation schemes. First, the irradiation effects are assessed on film level, sketching an overview of the dose-dependent changes in the magnetic energy landscape. Subsequent time-domain nucleation characteristics of irradiated nanostructures reveal substantial increases in the anisotropy fields but surprisingly small effects on the measured energy barriers, indicating shrinking nucleation volumes. Spatial control of the domain wall nucleation point is achieved by employing focused irradiation of pre-irradiated magnets, with the diameter of the introduced circular defect controlling the coercivity. Special attention is given to the nucleation mechanisms, changing from a Stoner-Wohlfarth particle's coherent rotation to depinning from an anisotropy gradient. Dynamic micromagnetic simulations and related measurements are used in addition to model and analyze this depinning-dominated magnetization reversal

Clinical Validation of PITX2 DNA Methylation to Predict Outcome in High-Risk Breast Cancer Patients Treated with Anthracycline-Based Chemotherapy

Background: Breast cancer patients at high risk for recurrence are treated with anthracycline-based chemotherapy, but not all patients do equally benefit from such a regimen. To further improve therapy decision-making, biomarkers predicting outcome are of high unmet medical need. Methods: The percent DNA methylation ratio (PMR) of the promoter gene coding for the Paired-like homeodomain transcription factor 2 (PITX2) was determined by a validated methylation-specific real-time polymerase chain reaction (PCR) test. The multicenter study was conducted in routinely collected archived formalin-fixed paraffin-embedded (FFPE) tissue from 205 lymph node-positive breast cancer patients treated with adjuvant anthracycline-based chemotherapy. Results: The cut-off for the PITX2 methylation status (PMR = 12) was confirmed in a randomly selected cohort (n = 60) and validated (n = 145) prospectively with disease-free survival (DFS) at the 10-year follow-up. DFS was significantly different between the PMR ≤ 12 versus the PMR > 12 group with a hazard ratio (HR) of 2.74 (p < 0.001) in the validation cohort and also for the patient subgroup treated additionally with endocrine therapy (HR 2.47; p = 0.001). Conclusions: Early-stage lymph node-positive breast cancer patients with low PITX2 methylation do benefit from adjuvant anthracycline-based chemotherapy. Patients with a high PITX2 DNA methylation ratio, approximately 30%, show poor outcome and should thus be considered for alternative chemotherapy regimens

Skyrmion velocities in FIB irradiated W/CoFeB/MgO thin films

In recent years magnetic skyrmions attracted great attention for the possibility to move them with low current density, their intrinsic stability and their robustness against defects and edge roughness compared to other magnetic textures. For applications, it is very important to be able to influence the behaviour of skyrmions locally. In this article, we present an evaluation on the effects of FIB Ga+ irradiation on skyrmion motion in W/CoFeB/MgO thin films. The influence of FIB irradiation is evaluated both, in terms of modification of the skyrmion Hall angle and the skyrmion velocity. An overview of the effects of the pulsing parameters on the skyrmion motion, shows low influence of the pulses rise-time and an external magnetic field. In addition the analysis after the irradiation shows that it influences notably the dynamics of skyrmions. In the irradiated zone the speed and angle of motion of these magnetic textures are strongly reduced. I. INTRODUCTIO

Skyrmions Under Control - FIB Irradiation as a Versatile Tool for Skyrmion Circuits

Magnetic data storage and processing offer certain advances over conventional technologies, amongst which non-volatility and low power operation are the most outstanding ones. Skyrmions are a promising candidate as a magnetic data carrier. However, the sputtering of skyrmion films and the control of the skyrmion nucleation, motion, and annihilation remains challenging. This article demonstrates that using optimized focused ion beam irradiation and annealing protocols enable to easily access the skyrmion phase in W/CoFeB/MgO thin-films. By analyzing ion beam engineered skyrmion hosting wires, excited by sub-100ns current pulses, possibilities to control skyrmion nucleation, guide their motion and control their annihilation are unfold. Overall, the key elements needed to develop extensive skyrmion networks are presented in this work. This article is protected by copyright. All rights reserved