Electronic structures and photoemission spectroscopy

Abstract:

Background

Primary hypertrophic osteoarthropathy (PHO) is a genetically and clinically heterogeneous systematic disorder caused by mutations in genes HPGD and SLCO2A1. The purpose of the present study is to provide useful information for the early and precise diagnosis of PHO and identify causative mutations in Chinese PHO children.

Methods and results

The clinical manifestations, radiographic features of seven Chinese pediatric patients were systematically analyzed. Targeted exome sequencing identified a previously reported c.310_311delCT mutation and a novel common splicing site mutation c.324 + 5G > A in the HPGD gene. Relative quantitative real time PCR validated a novel deletion of the exon 4 in the same gene. Neither mutations nor structural variations in the gene SLCO2A1 were detected.

Conclusions

In the present study, homozygous or compound heterozygous HPGD mutations were identified in seven Chinese pediatric patients, suggesting an autosomal recessive inheritance. The c.310_311delCT mutation and the splicing site mutation c.324 + 5G > A were likely to be mutational hotspots in Chinese PHO patients. For the first time, a structural variation of the HPGD gene was reported. Homozygous, compound heterozygous mutations or structural variation identified in the HPGD gene proposed that targeted exome sequencing may be a preferable method for pediatric PHO diagnosis and mutation analysis.

Abstract:

Ferromagnetic ordering in a topological insulator can break time-reversal symmetry, realizing dissipationless electronic states in the absence of a magnetic field. The control of the magnetic state is of great importance for future device applications. We provide a detailed systematic study of the magnetic state in highly doped CrxSb2−xTe3 thin films using electrical transport, magneto-optic Kerr effect measurements and terahertz time domain spectroscopy, and also report an efficient electric gating of ferromagnetic order using the electrolyte ionic liquid [DEME][TFSI]. Upon increasing the Cr concentration from x = 0.15 to 0.76, the Curie temperature (Tc) was observed to increase by ~5 times to 176 K. In addition, it was possible to modify the magnetic moment by up to 50% with a gate bias variation of just ±3 V, which corresponds to an increase in carrier density by 50%. Further analysis on a sample with x = 0.76 exhibits a clear insulator-metal transition at Tc, indicating the consistency between the electrical and optical measurements. The direct correlation obtained between the carrier density and ferromagnetism - in both electrostatic and chemical doping - using optical and electrical means strongly suggests a carrier-mediated Ruderman-Kittel-Kasuya-Yoshida (RKKY) coupling scenario. Our low-voltage means of manipulating ferromagnetism, and consistency in optical and electrical measurements provides a way to realize exotic quantum states for spintronic and low energy magneto-electronic device applications.