We report on the observation of Fermi edge enhanced resonant tunneling transport in a II-VI semiconductor heterostructure. The resonant transport through a self assembled CdSe quantum dot survives up to 45 K and probes a disordered two dimensional (2D) like emitter which dominates the magnetic field dependence of the transport. An enhancement of the tunnel current through many particle effects is clearly observable, even without an applied magnetic field. Additional fine structure in the tunneling current suggests that while conventional Fermi edge singularity theory successfull reproduces the general features of the increased transmission, it is not adequate to describe all details of the current enhancement.

We study I-V characteristics of an all-II-VI semiconductor resonant tunneling diode with dilute magnetic impurities in the quantum well layer. Bound magnetic polaron states form in the vicinity of potential fluctuations at the well interface while tunneling electrons traverse these interface quantum dots. The resulting microscopic magnetic order lifts the degeneracy of the resonant tunneling states. Although there is no macroscopic magnetization, the resulting resonant tunneling current is highly spin polarized at zero magnetic field due to the zero field splitting. Detailed modeling demonstrates that the local spin polarization efficiency exceeds 90% without an external magnetic field.

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We report on a process that enables the removal of II-VI semiconductor epilayers from their GaAs growth substrate and their subsequent transfer to arbitrary host environments. The technique combines mechanical lapping and layer selective chemical wet etching and is generally applicable to any II-VI layer stack. We demonstrate the non-invasiveness of the method by transferring an all-II-VI magnetic resonant tunneling diode. High resolution X-ray diffraction proves that the crystal integrity of the heterostructure is preserved. Transport characterization confirms that the functionality of the device is maintained and even improved, which is ascribed to completely elastic strain relaxation of the tunnel barrier layer. arXiv:1311.3803v1 [cond-mat.mtrl-sci]

BackgroundFor the past decades the mean age of primiparae in Western societies is constantly increasing. At the same time, there is a growing demand for assisted reproductive technologies such as in vitro fertilization and intracytoplasmic sperm injection. Subsequently, a higher prevalence of pregnancy-associated diseases such as gestational hypertension and preeclampsia is observed. To improve pregnancy rates after in vitro fertilization/intracytoplasmic sperm injection and to reduce the risk of pregnancy-associated diseases with a cardiovascular pathophysiology, two anticoagulants are the focus of current research: low molecular weight heparin and acetylsalicylic acid (aspirin).Case presentationA 41-year-old white woman, gravida 3, para 0, received low molecular weight heparin to reduce the risk of abortion after five unsuccessful intracytoplasmic sperm injections and two miscarriages. She autonomously discontinued the medication with low molecular weight heparin at 12 weeks and 2 days of gestation and took aspirin instead until 24 weeks and 2 days of gestation as preeclampsia prophylaxis. However, the pregnancy ended with an urgent cesarean section at 27 weeks and 4 days of gestation due to a fast progressing hemolysis, elevated liver enzyme levels, and low blood platelet count syndrome, a potentially life-threatening variant of preeclampsia.ConclusionBased on the current demographic trend toward late-in-life pregnancy it is mandatory to establish clear guidelines concerning preventive treatment options of preeclampsia for patients with risk factors. The establishment of a special first-trimester screening for these women should be discussed. Moreover, it is necessary to raise the awareness among physicians of these contemporary issues to guarantee the best possible medical care.Electronic supplementary materialThe online version of this article (10.1186/s13256-018-1943-1) contains supplementary material, which is available to authorized users.