Indication for the coexistence of closed orbit and quantum interferometer with the same cross section in the organic metal (ET)4(H3O)[Fe(C2O4)3].C6H4Cl2: Persistence of SdH oscillations above 30 K

Shubnikov-de Haas (SdH) and de Haas-van Alphen (dHvA) oscillations spectra of the quasi-two dimensional charge transfer salt $\beta$"-(ET)$_4$(H$_3$O)[Fe(C$_2$O$_4$)$_3$]$\cdot$C$_6$H$_4$Cl$_2$ have been investigated in pulsed magnetic fields up to 54 T. The data reveal three basic frequencies F$_a$, F$_b$ and F$_{b - a}$, which can be interpreted on the basis of three compensated closed orbits at low temperature. However a very weak thermal damping of the Fourier component F$_b$, with the highest amplitude, is evidenced for SdH spectra above about 6 K. As a result, magnetoresistance oscillations are observed at temperatures higher than 30 K. This feature, which is not observed for dHvA oscillations, is in line with quantum interference, pointing to a Fermi surface reconstruction in this compound.Comment: published in Eur. Phys. J. B 71 203 (2009

Cascade of field-induced magnetic transitions in a frustrated antiferromagnetic metal

Contains fulltext : 133179.pdf (publisher's version ) (Open Access

Fermi surface of SrFe2P2 determined by the de Haas- van Alphen effect

Contains fulltext : 145259.pdf (publisher's version ) (Open Access)5 p

Fermi surface of IrTe2 in the valence-bond state as determined by quantum oscillations

Contains fulltext : 149442.pdf (publisher's version ) (Open Access

Evolution of the fermi surface of BaFe2(As1-xPx)2 on entering the superconducting dome

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Millimetre-wave and magnetic studies on a high-spin molecule, Cr10{_{10}}(OMe)20{_{20}}(O2{_2}CCMe3{_3})10{_{10}}

We report millimetre-wave and magnetic measurements on single crystals of the high-spin molecular magnet, Cr$_{10}$(OMe)$_{20}$(O$_{2}$CCMe$_{3}$)$_{10}$. The susceptibility data obtained using a SQUID magnetometer indicate that this molecule has a total spin of $S=15$. The temperature dependence of the magnetisation allows us to estimate the intermolecular exchange constant. The EPR spectra were obtained at different frequencies, angles and temperatures. The results are compared with numerical simulations allowing determination of the Hamiltonian parameters

Anisotropic fluctuations and quasiparticle excitations in FeSe0:5Te0:5

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Suppression of superconductivity and enhanced critical field anisotropy in thin flakes of FeSe

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Více-pásový magnetotransport v exfoliovaných tenkých vrstvách CuxBi2Se3

We report magnetotransport studies in thin (<100 nm) exfoliated films of Cu x Bi2Se3 and we detect an unusual electronic transition at low temperatures. Bulk crystals show weak superconductivity with K and a possible electronic phase transition around 200 K. Following exfoliation, superconductivity is supressed and a strongly temperature dependent multi-band conductivity is observed for T < 30 K. This transition between competing conducting channels may be enhanced due to the presence of electronic ordering, and could be affected by the presence of an effective internal stress due to Cu intercalation. By fitting to the weak antilocalisation conductivity correction at low magnetic fields we confirm that the low temperature regime maintains a quantum phase coherence length nm indicating the presence of topologically protected surface states.Pojednáváme o magnetotransportních studiích na tenkých (<100 nm) exfoliovaných vrstvách CuxBi2Se3 a zjišťujeme neobvyklý elektronický přechod při nízkých teplotách. Objemové krystaly vykazují slabou supravodivost s Tc ~ 3,5 K a možný elektronický fázový přechod okolo 200 K. Po exfoliaci je supravodivost potlačena a silně teplotně závislá více-pásová vodivost je pozorována při T < 30 K. Tento přechod mezi konkurenčními vodivostními kanály může být zvýšen kvůli přítomnosti elektronického uspořádání a může být ovlivněn přítomností účinného vnitřního pnutí kvůli interkalaci Cu. Fitováním korekce na slabou nelokalizovanou vodivost při nízkých magnetických polích potvrzujeme, že nízkoteplotní režim udržuje kvantovou fázovou koherenční délku L>100 nm, což indikuje přítomnost topologicky chráněných povrchových stavů

The effect of magnetic ions and disorder on superconducting β′′\beta{''}-(BEDT-TTF)4{_4}[ (H3{_3}O)M(C2{_2}O4{_4})3{_3}] ⋅\cdot C6{_6}H5_5NO2{_2} salts, where M = Ga and Cr

We report magnetotransport measurements performed in magnetic fields of up to 33 T and at low temperatures (0.45 K$<$T$<$4.2 K) on two iso-structural superconducting charge-transfer salts, $\beta^{''}$-(BEDT-TTF)$_4$[ (H$_3$O)$M$(C$_2$O$_4$)$_3$] $\cdot$ C$_6$H$_5$NO$_2$, where the 3d metal ion $M$ is either non-magnetic Ga$^{3+}$ or magnetic Cr$^{3+}$. Quantum oscillations suggest that the salt with $M$ = Ga has two two-dimensional Fermi surface pockets (45 T and 230 T) whereas when $M$ = Cr only one pocket (230 T) is observed. Replacing Ga with Cr has the effect of enhancing the effective mass of the 230 T pocket from $1.2 \pm 0.2~m_{e}$ to $2.2 \pm 0.3~m_{e}$ and reducing the superconducting critical temperature from $T_{c}$ $\approx$ 8 K to $T_{c}$ $\approx$ 5 K. Key words. organic superconductors-quantum oscillations