The effect of the interlayer ordering on the Fermi surface of Kagome superconductor CsV3_3Sb5_5 revealed by quantum oscillations

The connection between unconventional superconductivity and charge density waves (CDW) has intrigued the condensed matter community and found much interest in the recently discovered superconducting Kagome family of AV$_3$Sb$_5$ (A = K, Cs, Rb). Xray diffraction and Raman spectroscopy measurements established that the CDW order in CsV$_3$Sb$_5$ comprises of a 2x2x4 structure with stacking of layers of star-of-David (SD) and inverse-star-of-David (ISD) pattern along the $c$-axis direction. Such interlayer ordering will induce a vast normalization of the electronic ground state; however, it has not been observed in Fermi surface measurements. Here we report quantum oscillations of CsV$_3$Sb$_5$ using tunnel diode oscillator frequency measurements. We observed a large number of frequencies, many of which were not reported. The number of frequencies can not be explained by DFT calculations when only SD or ISD distortion is considered. Instead, our results are consistent with calculations when interlayer ordering is taken into account, providing strong evidence that CDW phase of CsV$_3$Sb$_5$ has complicated structure distortion which in turn has dramatic effects on the Fermi surface properties.Comment: Accepted by Physical Review Letter

CoAs: The line of 3d demarcation

Transition metal-pnictide compounds have received attention for their tendency to combine magnetism and unconventional superconductivity. Binary CoAs lies on the border of paramagnetism and the more complex behavior seen in isostructural CrAs, MnP, FeAs, and FeP. Here we report the properties of CoAs single crystals grown with two distinct techniques along with density functional theory calculations of its electronic structure and magnetic ground state. While all indications are that CoAs is paramagnetic, both experiment and theory suggest proximity to a ferromagnetic instability. Quantum oscillations are seen in torque measurements up to 31.5~T, and support the calculated paramagnetic Fermiology.Comment: 10 pages, 6 figure

CoAs: The Line of 3d Demarcation

Transition metal-pnictide compounds have received attention for their tendency to combine magnetism and unconventional superconductivity. Binary CoAs lies on the border of paramagnetism and the more complex behavior seen in isostructural CrAs, MnP, FeAs, and FeP. Here we report the properties of CoAs single crystals grown with two distinct techniques along with density functional theory calculations of its electronic structure and magnetic ground state. While all indications are that CoAs is paramagnetic, both experiment and theory suggest proximity to a ferromagnetic instability. Quantum oscillations are seen in torque measurements up to 31.5 T and support the calculated paramagnetic Fermiology

Quantum Oscillations in the Anomalous Spin Density Wave State of FeAs

Quantum oscillations in the binary antiferromagnetic metal FeAs are presented and compared to theoretical predictions for the electronic band structure in the anomalous spin density wave state of this material. Demonstrating a method for growing single crystals out of Bi flux, we utilize the highest quality FeAs to perform torque magnetometry experiments up to 35 T, using rotations of field angle in two planes to provide evidence for one electron and one hole band in the magnetically ordered state. The resulting picture agrees with previous experimental evidence for multiple carriers at low temperatures, but the exact Fermi surface shape differs from predictions, suggesting that correlations play a role in deviation from ab initio theory and cause up to a fourfold enhancement in the effective carrier mass

Plant diversity in secondary, montane grasslands – a case study of the abandoned plantations of Mariepskop Mountain, South Africa

Grasslands are one of the most threatened terrestrial ecosystem types, and montane grasslands of particular conservation concern. Despite high rates of transformation in recent decades, croplands and plantations are being abandoned in parts of many countries, creating an opportunity for conservation of montane grasslands through restoration. We report on the changes in the cover of major vegetation types (indigenous forest, grassland, and plantations) between 1935 and 2022, in an area that was intensively afforested from 1930 to 1960 and abandoned in 2000. Montane grassland at the site declined from over 50% of all landcover to below 15%, but subsequently recovered to 30% within 20 years. Many former plantations developed into secondary grassland with estimated gamma plant species richness of 231 for herbaceous species and 45 for savanna species. These are high values considering the size of the study area (4000 ha), and comparable to estimates from primary grassland sites in the broader region. However, at the scale of 1 m2 sampling quadrats, richness in the secondary grasslands was below that recorded in the last remaining patches of primary grassland at the site (means of 2.6 versus 4.7 for graminoid species, and 1.9 versus 2.9 for forbs). Some of the former Eucalyptus plantations had transformed into novel savannas dominated by fire-tolerant, resprouting trees, and may require more active restoration. Secondary grasslands such as those reported on here could potentially make a significant contribution to the conservation of montane biodiversity over the coming decades, warranting further research (both socio-economic and ecological) on the factors that lead to abandonment and promote the emerge of secondary grasslands of high diversity

The Ursinus Weekly, November 19, 1951

Four soloists for Messiah concert named • Fraternities give out bids; Plan parties next week • Student-faculty talents presented for benefit of Campus Chest fund • Kiszonas is new senior class prexy • Red Cross disbands • WSGA hears plans for Student Union • Forum speaker says religious belief implies skeptical aspect • Curtain rises on Private Lives act tomorrow night • Nominees listed for \u2753 yearbook positions • Curtain Club play set for 2-night run • Student tells of conditions in Russia • Senior ball set • Campus Chest campaign reaches half-way mark • Haverford College student panel to argue army conscription here • Editorials: Thanksgiving, 1951; East is world headache • Gigi, French play, opens at Philadelphia theater • Alumni • Letters to the editor • Dr. McClure delivers lecture on education • If Collegeville were in Korea, this could happen • Thanksgiving: Pre and Post • Messiah tradition came with Dr. Philip • Bruins to play benefit in York • East Stroudsburg handed initial defeat by Belles • Bears defeated in finale by unbeaten Susquehanna • Curtis Hall wins interdorm title • Women begin to play in intramural hockey • Susquehanna completes unbeaten, untied year • Band attacked for disinterest • Soccer squad closes its season by losing to Franklin & Marshall team • Nevison lectures to Chem society • Intercollegiate bridge tournament to begin • Pediatrics talk given pre-medders • Square dance enjoyedhttps://digitalcommons.ursinus.edu/weekly/1528/thumbnail.jp