456 research outputs found
Role of anion size, magnetic moment, and disorder on the properties of the organic conductor kappa-(BETS)_2Ga_{1-x}Fe_{x}Cl_{4-y}_Br_{y}
Shubnikov-de Haas and angular dependent magnetoresistance oscillations have
been used to explore the role of anion size, magnetic moment, and disorder in
the organic conductors kappa-(BETS)_2GaBr_{4} and kappa-(BETS)_2FeCl_{2}_Br_{2}
in the isomorphic class kappa-(BETS)_2Ga_{1-x}Fe_{x}Cl_{4-y}_Br_{y}. The
results, combined with previous work, show correlations between the anion
composition (Ga_{1-x}Fe_{x}Cl_{4-y}_Br_{y}) and the superconducting transition
temperature, effective mass, Fermi surface topology, and the mean free path.Comment: 5 pages, 6 figure
Kemitraan Pemerintah dan Swasta dalam Pembangunan Bandara Swadaya Sangia Nibandera Kabupaten Kolaka
Penelitian ini bertujuan menjelaskan konsep kemitraan dalam pembangunan bandara Swadaya di Kabupaten Kolaka, dengan melihat dari mekanisme, struktur dan insentif dari kemitraan.Metode yang digunakan adalah metode kualitatif deskriptif. Data dianalisis dengan reduksi data, penyajian data, dan menarik kesimpulan.Hasil Penelitian ini menunjukkan bahwa dari pelaksanaan kemitraan antara Pemerintah Kabupaten Kolaka dan Swasta dalam Pembangunan Bandar Udara Swadaya Sangia Nibandera di Kabupaten Kolaka diihat dari mekanisme, struktur dan insentif terlaksana dengan baik dan efektif. Dari pelaksanaan kemitraan ini memberikan manfaat bagi masyarakat Kabupaten Kolaka dengan meningkatnya pendapatan dan juga memudahkan masuknya Investor di Kabupaten Kolaka
Superconductivity in an organic insulator at very high magnetic fields
We investigate by electrical transport the field-induced superconducting
state (FISC) in the organic conductor -(BETS)FeCl. Below 4 K,
antiferromagnetic-insulator, metallic, and eventually superconducting (FISC)
ground states are observed with increasing in-plane magnetic field. The FISC
state survives between 18 and 41 T, and can be interpreted in terms of the
Jaccarino-Peter effect, where the external magnetic field {\em compensates} the
exchange field of aligned Fe ions. We further argue that the Fe
moments are essential to stabilize the resulting singlet, two-dimensional
superconducting stateComment: 9 pages 3 figure
Magnetic-field-induced superconductivity in layered organic molecular crystals with localized magnetic moments
The synthetic organic compound lambda-(BETS)2FeCl4 undergoes successive
transitions from an antiferromagnetic insulator to a metal and then to a
superconductor as a magnetic field is increased. We use a Hubbard-Kondo model
to clarify the role of the Fe(3+) magnetic ions in these phase transitions. In
the high-field regime, the magnetic field acting on the electron spins is
compensated by the exchange field He due to the magnetic ions. This suggests
that the field-induced superconducting state is the same as the zero-field
superconducting state which occurs under pressure or when the Fe(3+) ions are
replaced by non-magnetic Ga(3+) ions. We show how He can be extracted from the
observed splitting of the Shubnikov-de Haas frequencies. Furthermore, we use
this method of extracting He to predict the field range for field-induced
superconductivity in other materials.Comment: 5 page
The High Magnetic Field Phase Diagram of a Quasi-One Dimensional Metal
We present a unique high magnetic field phase of the quasi-one dimensional
organic conductor (TMTSF)ClO. This phase, termed "Q-ClO", is
obtained by rapid thermal quenching to avoid ordering of the ClO anion. The
magnetic field dependent phase of Q-ClO is distinctly different from that
in the extensively studied annealed material. Q-ClO exhibits a spin density
wave (SDW) transition at 5 K which is strongly magnetic field
dependent. This dependence is well described by the theoretical treatment of
Bjelis and Maki. We show that Q-ClO provides a new B-T phase diagram in the
hierarchy of low-dimensional organic metals (one-dimensional towards
two-dimensional), and describe the temperature dependence of the of the quantum
oscillations observed in the SDW phase.Comment: 10 pages, 4 figures, preprin
Experimental study on compressive strength and infiltration rate of pervious concrete containing recycled coarse aggregate and seawater
In this study, pervious concrete specimens were created containing 100 percent of Recycled Coarse Aggregate (RCA) as a replacement for Natural Coarse Aggregate (NCA) and seawater as a replacement for Fresh Water (FW). Eighteen specimen tests in total were prepared which consisted of nine specimens containing Recycled Coarse Aggregate Seawater (RCAS) concrete and nine specimens containing Recycled Coarse Aggregate Fresh-water (RCAF) as control concrete. Both water to cement ratio of 0.45 and RCA to cement ratio of 0.25 is determined and the mix design is calculated. Fresh concrete was cast on the cylindrical mold of 150 x 300mm in a porous formation. Then the compressive strength and infiltration rate tests were conducted to understand the performance of RCA mixed seawater (SW) at curing times of 3, 7, and 28 days. The results show that the compressive strength of RCAS can reach a peak of around 8.98 MPa compared with RCAF just around 7.27 MPa in maximum curing of 28 days and the value of RCAS samples shows that the infiltration rate is increasing linearly as compressive strength is from three days to 28 days
Phase Diagram of Pressure-Induced Superconductivity in EuFe2As2 Probed by High-Pressure Resistivity up to 3.2 GPa
We have constructed a pressuretemperature () phase diagram of
-induced superconductivity in EuFeAs single crystals, via
resistivity () measurements up to 3.2 GPa. As hydrostatic pressure is
applied, an antiferromagnetic (AF) transition attributed to the FeAs layers at
shifts to lower temperatures, and the corresponding resistive
anomaly becomes undetectable for 2.5 GPa. This suggests that the
critical pressure where becomes zero is about 2.5
GPa. We have found that the AF order of the Eu moments survives up to
3.2 GPa without significant changes in the AF ordering temperature
. The superconducting (SC) ground state with a sharp transition
to zero resistivity at 30 K, indicative of bulk
superconductivity, emerges in a pressure range from 2.5
GPa to 3.0 GPa. At pressures close to but outside the SC phase, the
curve shows a partial SC transition (i.e., zero resistivity is not
attained) followed by a reentrant-like hump at approximately
with decreasing temperature. When nonhydrostatic pressure with a uniaxial-like
strain component is applied using a solid pressure medium, the partial
superconductivity is continuously observed in a wide pressure range from 1.1
GPa to 3.2 GPa.Comment: 7 pages, 6 figures, accepted for publication in Physical Review B,
selected as "Editors' Suggestion
The Fulde-Ferrell-Larkin-Ovchinnikov State in the Organic Superconductor k-(BEDT-TTF)2Cu(NCS)2 as Observed in Magnetic Torque Experiments
We present magnetic-torque experiments on the organic superconductor
k-(BEDT-TTF)2Cu(NCS)2 for magnetic fields applied parallel to the 2D
superconducting layers. The experiments show a crossover from a second-order to
a first-order transition when the upper critical field reaches 21 T. Beyond
this field, which we interpret as the Pauli limit for superconductivity, the
upper critical field line shows a pro-nounced upturn and a phase transition
line separates the superconducting state into a low- and a high-field phase. We
interpret the data in the framework of a Fulde-Ferrell-Larkin-Ovchinnikov
state.Comment: 2 pages, 1 figur
Fiber-coupled Antennas for Ultrafast Coherent Terahertz Spectroscopy in Low Temperatures and High Magnetic Fields
For the purposes of measuring the high-frequency complex conductivity of
correlated-electron materials at low temperatures and high magnetic fields, a
method is introduced for performing coherent time-domain terahertz spectroscopy
directly in the cryogenic bore of existing dc and pulsed magnets. Miniature
fiber-coupled THz emitters and receivers are constructed and are demonstrated
to work down to 1.5 Kelvin and up to 17 Tesla, for eventual use in higher-field
magnets. Maintaining the sub-micron alignment between fiber and antenna during
thermal cycling, obtaining ultrafast (~fs) optical gating pulses at the
end of long optical fibers, and designing highly efficient devices that work
well with low-power optical gating pulses constitute the major technical
challenges of this project. Data on a YBCO superconducting thin film and a high
mobility 2D electron gas is shown.Comment: 8 pages, 9 figure
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