ABSTRACT
Skyrmions are of interest both from a fundamental and technological point of view, due to their potential to act as information carriers. But one challenge concerns their manipulation, especially at high temperature where thermal fluctuations eventually disintegrate them. Here we study the competition between skyrmions and a chiral spin liquid, using the latter as an entropic buffer to impose a quasivacuum of skyrmions. As a result, the temperature becomes a knob to tune the skyrmion density from a dense liquid to a diluted gas, protecting the integrity of each skyrmion from paramagnetic disintegration. With this additional knob in hand, we find at high field a topological spin glass made of zero- and one-dimensional topological defects (respectively skyrmions and bimerons).
ABSTRACT
Magnetic skyrmions are topological solitons with a nanoscale winding spin texture that hold promise for spintronics applications1-4. Skyrmions have so far been observed in a variety of magnets that exhibit nearly parallel alignment for neighbouring spins, but theoretically skyrmions with anti-parallel neighbouring spins are also possible. Such antiferromagnetic skyrmions may allow more flexible control than conventional ferromagnetic skyrmions5-10. Here, by combining neutron scattering measurements and Monte Carlo simulations, we show that a fractional antiferromagnetic skyrmion lattice is stabilized in MnSc2S4 through anisotropic couplings. The observed lattice is composed of three antiferromagnetically coupled sublattices, and each sublattice is a triangular skyrmion lattice that is fractionalized into two parts with an incipient meron (half-skyrmion) character11,12. Our work demonstrates that the theoretically proposed antiferromagnetic skyrmions can be stabilized in real materials and represents an important step towards their implementation in spintronic devices.
ABSTRACT
INTRODUCCIÓN: En comparación con pandemias anteriores por otros virus, el SARS-CoV-2 ha afectado a la población obstétrica en menor número, por lo que registrar la historia clínica en pacientes con COVID 19 de nuestra población se hacía imperativo. METODOLOGÍA: Se realizó un estudio descriptivo transversal no analítico en la maternidad del Hospital El Pino. Se realizaron test PCR para SARS-CoV-2 entre abril y junio del 2020 a todas las usuarias con: (1) síntomas sugerentes de COVID 19, (2) antecedente de contacto estrecho o (3) que requiera hospitalización independientemente del motivo. En ellas se analizaron variables demográficas, evolución clínica y se estimaron "outcomes" obstétricos. RESULTADOS: Se tomaron 409 PCR y de éstas 365 en población obstétrica alcanzando en ella una incidencia acumulada de positividad de 19.7%. El 55.6% (40 pacientes) asintomáticas, 4.2% (9 pacientes) contacto estrecho y 40.3% (29 pacientes) sintomáticas. De estas pacientes la mayoría resulto ser de nacionalidad chilena (79.2%) con una prevalencia de HTA y DM tipo 1 o 2 entre el 8-10%. La media de la edad gestacional en la cual se realizó el diagnóstico fue en el 3er trimestre y la del momento del parto fue de 37.1 semanas (+/-3.9). Los síntomas más comunes presentados fueron tos, cefalea y mialgias; sin embargo, 7 requirieron ingreso a unidad de cuidados intensivos. En el seguimiento de usuarias asintomáticas 6,9% y 2,8% presentaron síntomas al día 7 y 14 respectivamente. CONCLUSIONES: La pandemia SARS-CoV-2 ha afectado la población obstetrica de igual manera, presentandose en su mayoría de forma asintomática, destacando la importancia del screening universal a la hora de hospitalizar nuestras usuarias y evitar transmisión intrahospitalaria.
INTRODUCTION: Compared to previous pandemics caused by other viruses, SARS-CoV-2 has affected the obstetric population in a smaller number, thus recording the medical history in patients with COVID 19 in our population became imperative. METHODOLOGY: A non-analytical, cross-sectional descriptive study was carried out in the maternity section of Hospital El Pino. PCR tests for SARS-CoV-2 were performed between April and June 2020 to all patients with: (1) symptoms suggestive of COVID 19, (2) a history of close contact or (3) requiring hospitalization regardless of motive. In them, demographic variables, clinical evolution were analysed and obstetric outcomes were estimated. RESULTS: 409 PCR were taken, raising a cumulative incidence of positivity of 19.7%. 55.6% (40 patients) were asymptomatic, 4.2% (9 patients) were close contact and 40.3% (29 patients) symptomatic. Within these patients, the majority turned out to be Chilean (79.2%) with a prevalence of HT and DM type 1 or 2 between 8-10%. The average of the gestational age at which the diagnosis was made was in the 3rd trimester and that of the moment of delivery was 37.1 weeks (+/- 3.9). The most common symptoms presented were cough, headache and myalgia, however, 7 patients required admission to the intensive care unit. In the monitoring stage of asyntomatic patients, 6.9% and 2.8% had symptoms on day 7 and 14 respectively. CONCLUSIONS: The SARS-CoV-2 pandemic has affected the obstetric population with no difference, with the majority presenting asymptomatic, fact which highlights the importance of universal screening when hospitalizing our users and avoiding intra-hospital transmission.
