A quantum spin liquid is a state of matter where unpaired electrons’ spins, although entangled, do not show magnetic order even at the zero temperature. The realization of a quantum spin liquid is a ...long-sought goal in condensed-matter physics. Although neutron scattering experiments on the two-dimensional spin-1/2 kagome lattice ZnCu3(OD)6Cl2 and triangular lattice YbMgGaO4 have found evidence for the hallmark of a quantum spin liquid at very low temperature (a continuum of magnetic excitations), the presence of magnetic and non-magnetic site chemical disorder complicates the interpretation of the data. Recently, the three-dimensional Ce3+ pyrochlore lattice Ce2Sn2O7 has been suggested as a clean, effective spin-1/2 quantum spin liquid candidate, but evidence of a spin excitation continuum is still missing. Here, we use thermodynamic, muon spin relaxation and neutron scattering experiments on single crystals of Ce2Zr2O7, a compound isostructural to Ce2Sn2O7, to demonstrate the absence of magnetic ordering and the presence of a spin excitation continuum at 35 mK. With no evidence of oxygen deficiency and magnetic/non-magnetic ion disorder seen by neutron diffraction and diffuse scattering measurements, Ce2Zr2O7 may be a three-dimensional pyrochlore lattice quantum spin liquid material with minimum magnetic and non-magnetic chemical disorder.
Thermal expansion, electrical resistivity, magnetization, and specific heat measurements were performed on URu
Fe
Si
single crystals for various values of Fe concentration x in both the hidden-order ...(HO) and large-moment antiferromagnetic (LMAFM) regions of the phase diagram. Our results show that the paramagnetic (PM) to HO and LMAFM phase transitions are manifested differently in the thermal expansion coefficient. The uniaxial pressure derivatives of the HO/LMAFM transition temperature T
change dramatically when crossing from the HO to the LMAFM phase. The energy gap also changes consistently when crossing the phase boundary. In addition, for Fe concentrations at x
≈ 0.1, we observe two features in the thermal expansion upon cooling, one that appears to be associated with the transition from the PM to the HO phase and another one at lower temperature that may be due to the transition from the HO to the LMAFM phase.
Thulium fiber laser (TFL) is a safe and effective laser technique for conservative treatment of upper urinary tract carcinoma (UTUC). Effective tumor ablation and hemostasis were achieved without any ...major complications. Prospective randomized studies in larger populations with longer-term follow-up using different laser sources are required to confirm the effectiveness and safety of TFL in conservative UTUC treatment.
Few clinical data are available on thulium fiber laser (TFL) and conservative treatment of upper urinary tract urothelial carcinoma (UTUC).
To assess the effectiveness and safety of TFL in the conservative treatment of UTUC in terms of both tumor ablation and complication rates in a short-term follow-up.
Retrospective data were collected from all patients who underwent endoscopic management of UTUC between January 2021 and April 2022. All patients with nonmetastatic UTUC who were deemed suitable candidates (low- and high-grade disease) for conservative treatment were reviewed.
All patients underwent ureteroscopy with biopsy and at 2, 6, and 12 mo after the first surgery. UTUC ablation was achieved using TFL.
Clinical data were collected in a dedicated database. Intra- and postoperative outcomes were assessed. A descriptive statistical analysis was performed.
In total, 28 patients were evaluated. Thirteen patients (46.4%) were included in the low-risk UTUC treatment group and 15 (53.6%) in the high-risk group. The mean tumor size was 15.3 ± 5.7 mm. Biopsy showed low- and high-grade UTUCs in 19 and eight patients, respectively. Only one biopsy was inconclusive for achieving a diagnosis. At the second procedure biopsy, no tumor was found in 19 cases (70.4%), whereas seven had tumors confirmed (25.9%). To date, 23 and 17 out of 26 patients completed the 6- and 12-mo follow-up, respectively. UTUC recurrence was detected in five of 23 patients (21.7%) and in three of 17 patients (17.7%) at 6 and 12 mo, respectively. A total of 95 procedures were performed. No intraoperative complications were observed. In ten of the 95 procedures (10.5%), Clavien-Dindo grade I–II postoperative complications were experienced. Only one grade IIIB postoperative complication was noted.
TFL is a safe and effective technique for conservative treatment of UTUC in a short-term follow-up. Optimal tumor ablation and fine hemostatic control were achieved without major complications.
In this study, we looked at the outcomes of upper urinary tract tumors conservatively treated with the new thulium fiber laser (TFL). We conclude that TFL represents a safe and effective technique for the treatment of this kind of tumors in a short-term follow-up.
Here we report the fabrication and electrical characterization of high-transition temperature SQUIDs directly written by helium ion beam irradiation for use in Quantum Design's pulsed tube cooler ...based physical property measurement system. Our device consists of a SQUID with a direct coupled 300 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>m diameter flux focusing pickup loop. When DC biased above the critical current, we observe a modulation in the voltage with a peak-to-peak amplitude of 500 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>V, while having periodicity of 275 nT per flux quantum. The SQUID chip was mounted to the temperature-controlled system equipped with optically aligned piezo scanners which allow the accurate positioning of the sample less than 100 <inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>m from the sensor. The system functions as a magnetic properties characterization tool which can operate over a wide temperature range (1-50 K) without thermally isolating the SQUID from the sample.
In this paper, we describe an ultrasensitive differential capacitive dilatometer (<inline-formula> <tex-math notation="LaTeX">\Delta \text{L} </tex-math></inline-formula>/L ~ 10 −9 ) and novel ...ratiometric measurement method in the temperature range of 1.9 K < T <400 K for the investigation of thermal expansion and magnetostriction of single crystal as well as polycrystalline samples. The dilatometer provides a capacitive measurement based on a differential capacitance or the capacitance ratio measured between two parallel plate capacitors of the dilatometer. In this regard, an absolute capacitance bridge is not required, and even more advantageously, the effect of adsorbed gas on the capacitor plates is greatly reduced compared to conventional dilatometers. The differential capacitive dilatometer provides a symmetrical configuration which reduces the effect of temperature gradients. The capabilities of the dilatometer are demonstrated by the measurement of magnetic ordering of a URu 2 Si 2 sample, and of de Haas-van Alphen oscillations in an aluminum sample.
Here we report the fabrication and electrical characterization of high-transition temperature SQUIDs directly written by helium ion beam irradiation for use in Quantum Design's pulsed tube cooler ...based physical property measurement system. Our device consists of a SQUID with a direct coupled 300 Formula Omittedm diameter flux focusing pickup loop. When DC biased above the critical current, we observe a modulation in the voltage with a peak-to-peak amplitude of 500 Formula OmittedV, while having periodicity of 275 nT per flux quantum. The SQUID chip was mounted to the temperature-controlled system equipped with optically aligned piezo scanners which allow the accurate positioning of the sample less than 100 Formula Omittedm from the sensor. The system functions as a magnetic properties characterization tool which can operate over a wide temperature range (1–50 K) without thermally isolating the SQUID from the sample.
The molecular wheel Cr
(OMe)
(O
CCMe
)
, abbreviated {Cr
}, with an unusual intermediate total spin
= 9 and non-negligible cluster anisotropy,
/
= -0.045(2) K, is a rare case among wheels based on an ...even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state (
= 0). Herein, we unveil the origin of such a behavior. Angular magnetometry measurements performed on a single crystal confirmed the axial anisotropic behavior of {Cr
}. For powder samples, the temperature dependence of the susceptibility plotted as χ
(
) showed an overall ferromagnetic (FM) behavior down to 1.8 K, whereas the magnetization curve
(
) did not saturate at the expected 30 μ
/fu for 10 FM coupled 3/2 spin Cr
ions, but to a much lower value, corresponding to
= 9. In addition, the X-ray magnetic circular dichroism (XMCD) measured at high magnetic field (170 kOe) and 7.5 K showed the polarization of the cluster moment up to 23 μ
/fu. The magnetic results can be rationalized within a model, including the cluster anisotropy, in which the {Cr
} wheel is formed by two semiwheels, each with four Cr
spins FM coupled (
/
= 2.0 K), separated by two Cr
ions AF coupled asymmetrically (
/
=
/
= -2.0 K;
/
=
/
= -0.25 K). Inelastic neutron scattering and heat capacity allowed us to confirm this model leading to the
= 9 ground state and first excited
= 8. Single-molecule magnet behavior with an activation energy of
/
= 4.0(5) K in the absence of applied field was observed through ac susceptibility measurements down to 0.1 K. The intriguing magnetic behavior of {Cr
} arises from the detailed asymmetry in the molecule interactions produced by small-angle distortions in the angles of the Cr-O-Cr alkoxy bridges coupling the Cr
ions, as demonstrated by
and density functional theory calculations, while the cluster anisotropy can be correlated to the single-ion anisotropies calculated for each Cr
ion in the wheel.
The molecular wheel Cr10(OMe)20(O2CCMe3)10, abbreviated {Cr10}, with an unusual intermediate total spin S = 9 and non-negligible cluster anisotropy, D/k B = −0.045(2) K, is a rare case among wheels ...based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state (S = 0). Herein, we unveil the origin of such a behavior. Angular magnetometry measurements performed on a single crystal confirmed the axial anisotropic behavior of {Cr10}. For powder samples, the temperature dependence of the susceptibility plotted as χT(T) showed an overall ferromagnetic (FM) behavior down to 1.8 K, whereas the magnetization curve M(H) did not saturate at the expected 30 μB/fu for 10 FM coupled 3/2 spin Cr3+ ions, but to a much lower value, corresponding to S = 9. In addition, the X-ray magnetic circular dichroism (XMCD) measured at high magnetic field (170 kOe) and 7.5 K showed the polarization of the cluster moment up to 23 μB/fu. The magnetic results can be rationalized within a model, including the cluster anisotropy, in which the {Cr10} wheel is formed by two semiwheels, each with four Cr3+ spins FM coupled (J FM/k B = 2.0 K), separated by two Cr3+ ions AF coupled asymmetrically (J 23/k B = J 78/k B = −2.0 K; J 34/k B = J 89/k B = −0.25 K). Inelastic neutron scattering and heat capacity allowed us to confirm this model leading to the S = 9 ground state and first excited S = 8. Single-molecule magnet behavior with an activation energy of U/k B = 4.0(5) K in the absence of applied field was observed through ac susceptibility measurements down to 0.1 K. The intriguing magnetic behavior of {Cr10} arises from the detailed asymmetry in the molecule interactions produced by small-angle distortions in the angles of the Cr–O–Cr alkoxy bridges coupling the Cr3+ ions, as demonstrated by ab initio and density functional theory calculations, while the cluster anisotropy can be correlated to the single-ion anisotropies calculated for each Cr3+ ion in the wheel.
We have developed a commercial apparatus to measure the ac-susceptibility of small samples (1-500 mg) from 50 mK to 4 K using a versatile top loading dilution refrigerator. This susceptometer is ...readily available to perform fully automated ac measurements in both, cryogen free and liquid cooled Physical Property Measuring Systems (PPMS). AC susceptibility measurements can be performed with ac excitation fields in the range of 1 μT-0.4 mT (peak) for frequencies from 10 Hz to 10 kHz and in the presence of a static dc field of up to 12 T. The design of the susceptometer employs a novel approach that virtually eliminates heating of the sample stage by thermally anchoring the coil set at 1.8 K, using superconducting wire for the excitation coil, and using a coil design that limits induced eddy currents on the dilution unit. The sample is mounted to a sapphire sample holder attached to the dilution stage and positioned in the center of one of the pickup coils. An additional trim coil on the coil set allows for dynamic removal of any background signals during the measurement, facilitating sample measurements for moments as small as 2 × 10 -10 A·m 2 . We present measurements for various samples to demonstrate the capabilities and performance of this new instrument. In the current design, ac susceptibility measurements down to 50 mK can be performed in less than 8 h after mounting the sample.
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