The iridium double perovskite Sr2YIrO6 revisited: A combined structural and specific heat study

Recently, the iridate double perovskite Sr$_2$YIrO$_6$ has attracted considerable attention due to the report of unexpected magnetism in this Ir$^{5+}$ (5d$^4$) material, in which according to the J$_{eff}$ model, a non-magnetic ground state is expected. However, in recent works on polycrystalline samples of the series Ba$_{2-x}$Sr$_x$YIrO$_6$ no indication of magnetic transitions have been found. We present a structural, magnetic and thermodynamic characterization of Sr$_2$YIrO$_6$ single crystals, with emphasis on the temperature and magnetic field dependence of the specific heat. Here, we demonstrate the clue role of single crystal X-ray diffraction on the structural characterization of the Sr$_2$YIrO$_6$ double perovskite crystals by reporting the detection of a $\sqrt{2}a \times \sqrt{2}a \times 1c$ supercell, where $a$, $b$ and $c$ are the unit cell dimensions of the reported monoclinic subcell. In agreement with the expected non-magnetic ground state of Ir$^{5+}$ (5d$^4$) in Sr$_2$YIrO$_6$, no magnetic transition is observed down to 430~mK. Moreover, our results suggest that the low temperature anomaly observed in the specific heat is not related to the onset of long-range magnetic order. Instead, it is identified as a Schottky anomaly caused by paramagnetic impurities present in the sample, of the order of $n \sim 0.5(2)$ \%. These impurities lead to non-negligible spin correlations, which nonetheless, are not associated with long-range magnetic ordering.Comment: 20 pages, 10 figure

Iridium double perovskite Sr2YIrO6: A combined structural and specific heat study

© 2017 American Physical Society.Recently, the iridate double perovskite Sr2YIrO6 has attracted considerable attention due to the report of unexpected magnetism in this Ir5+ (5d4) material, in which according to the Jeff model, a nonmagnetic ground state is expected. However, in recent works on polycrystalline samples of the series Ba2-xSrxYIrO6 no indication of magnetic transitions have been found. We present a structural, magnetic, and thermodynamic characterization of Sr2YIrO6 single crystals, with emphasis on the temperature and magnetic field dependence of the specific heat. As determined by x-ray diffraction, the Sr2YIrO6 single crystals have a cubic structure, with space group Fm3m. In agreement with the expected nonmagnetic ground state of Ir5+ (5d4) in Sr2YIrO6, no magnetic transition is observed down to 430 mK. Moreover, our results suggest that the low-temperature anomaly observed in the specific heat is not related to the onset of long-range magnetic order. Instead, it is identified as a Schottky anomaly caused by paramagnetic impurities present in the sample, of the order of n∼0.5(2)%. These impurities lead to non-negligible spin correlations, which nonetheless, are not associated with long-range magnetic ordering

Observation of heavy spin-orbit excitons propagating in a nonmagnetic background: The case of (Ba,Sr)2YIrO6

We present a combined experimental and theoretical study of the elementary magnetic excitations in Ba2YIrO6 and Sr2YIrO6 - the two most intensively discussed candidates for a new type of magnetic instability caused by exciton condensation. For both materials, high-resolution resonant inelastic x-ray scattering (RIXS) at the Ir L3 edge reveals sharp excitations around 370 and 650 meV energy loss, which we identify as triplet and quintet spin-orbit excitons. While the momentum-dependent RIXS spectra reveal that both the triplet and the quintet propagate coherently within the nonmagnetic background of the singlet sites, these modes remain fully gapped. The Ir-Ir exchange interactions in both double perovskites are therefore not strong enough to overcome the magnetic gap and, hence, our results exclude an intrinsic magnetic instability due to a condensation of magnetic excitations for both Ba2YIrO6 and Sr2YIrO6

Is video-assisted mediastinoscopy superior than standard mediastinoscopy for mediastinal staging of the patients with lung cancer?

Background: In this study, we aimed to compare standard mediastinoscopy (SM) with video-assisted mediastinoscopy (VAM) for mediastinal staging of the patients with lung cancer in terms of safety profile, complication rates, mediastinal station, and lymph node counts. Methods: Data of 551 patients who were admitted to our clinic between January 2006 and January 2011 with the diagnosis of non-small cell lung cancer (NSCLC) and were scheduled for surgery were retrospectively analyzed. Age and sex of the patients and cell type of the tumor were recorded. A total of 361 patients (65.5%) had SM, while 190 patients (34.5%) had VAM. Results: Of the patients, 63.2% (n=96) who underwent VAM and 70.1% (n=218) who underwent SM were diagnosed with squamous cell carcinoma. N2 nodal involvement was detected in 66 of 361 patients (18.3%) who underwent SM and 60 of 190 patients (31.6%) who underwent VAM (p<0.001). Sensitivity was 87% and 79% at VAM and SM, respectively. Major hemorrhage was observed in four patients (1.1%) during SM, while none of the patients in the VAM group experienced such complication (p=0.3). Conclusion: Our study results suggest that VAM is a safe and invaluable method to be used in preoperative mediastinal staging of the patients with lung cancer. We believe that the main superiority of VAM over SM is the prevention of hemorrhage

Factors Affecting Postoperative Morbidity and Mortality in Patients Who Received Neoadjuvant Therapy for Lung Cancer

Aim: The aim of this study was to investigate the factors that affect mortality and morbidity (MM) in patients with non-small lung cell cancer (NSCLC) who received Neoadjuvant Therapy (NT) for mediastinal lymph node invasion (M LN I) before the surgery. Material and Method: Twentyfour NSCLC patients who received NT for M LN I before surgery were selected as the study group. Thirty patients who were operated without receving NT were constituted the control group. Major complications (MAC) including pneumonia, empyema, chylothorax Minor complications (MIC) including prolonged air leak, arrhythmia, anemia, hoarseness, and wound site infection were determined. Patients were evaluated retrospectively. Results: It was found that life threatening postoperative MAC increased significantly after NT (p=0.04), and MIC or factors causing them did'nt affect the morbidity, NT had no effect on survival. Discussion: Surgery for NSCLC after NT for MLNI increases major morbidities. Careful preoperative assessment, experienced surgical team and appropriate intensive care conditions will reduce MM. Therefore the risk of MM should minimized with wider and prospective studies