304 research outputs found
Candidate Quantum Spin Liquid in the Ce\textsuperscript{3+} Pyrochlore Stannate CeSnO
We report the low temperature magnetic properties of CeSnO, a
rare-earth pyrochlore. Our susceptibility and magnetization measurements show
that due to the thermal isolation of a Kramers doublet ground state,
CeSnO has Ising-like magnetic moments of
. The magnetic moments are confined to the local trigonal axes,
as in a spin ice, but the exchange interactions are antiferromagnetic. Below 1
K the system enters a regime with antiferromagnetic correlations. In contrast
to predictions for classical -Ising spins on the
pyrochlore lattice, there is no sign of long-range ordering down to 0.02 K. Our
results suggest that CeSnO features an antiferromagnetic liquid
ground state with strong quantum fluctuations.Comment: 6 pages, 4 figure
Magnetic structure and dynamics of a strongly one-dimensional cobalt metal-organic framework
We investigate the magnetism of the
Co(OH)(CHO) metal-organic framework which
displays complex inorganic chains separated from each other by distances of 1
to 2 nm, and which orders at ~5.4 K. The zero-field magnetic structure is
determined using neutron powder diffraction: it is mainly antiferromagnetic but
posseses a ferromagnetic component along the -axis. This magnetic
structure persists in presence of a magnetic field. Ac susceptibility
measurements confirm the existence of a single thermally activated regime over
7 decades in frequency () whereas time-dependent relaxation
of the magnetization after saturation in an external field leads to a two times
smaller energy barrier. These experiments probe the slow dynamics of domain
walls within the chains: we propose that the ac measurements are sensitive to
the motion of existing domain walls within the chains, while the magnetization
measurements are governed by the creation of domain walls.Comment: 12 pages, 14 figure
Single crystal growth, structure and magnetic properties of Pr2Hf2O7 pyrochlore
Large single crystals of the pyrochlore Pr2Hf2O7 have been successfully grown
by the floating zone technique using an optical furnace equipped with high
power Xenon arc lamps. Structural investigations have been carried out by both
synchrotron X-ray and neutron powder diffraction to establish the
crystallographic structure of the materials produced. The magnetic properties
of the single crystals have been determined for magnetic fields applied along
different crystallographic axes. The results reveal that Pr2Hf2O7 is an
interesting material for further investigations as a frustrated magnet. The
high quality of the crystals produced make them ideal for detailed
investigations, especially those using neutron scattering techniques.Comment: Accepted for publication in J. Phys.: Condens. Matte
Candidate quantum spin ice in the pyrochlore PrHfO
We report the low temperature magnetic properties of the pyrochlore
PrHfO. Polycrystalline and single-crystal samples are investigated
using time-of-flight neutron spectroscopy and macroscopic measurements,
respectively. The crystal-field splitting produces a non-Kramers doublet ground
state for Pr, with Ising-like anisotropy. Below 0.5 K ferromagnetic
correlations develop, which suggests that the system enters a spin ice-like
state associated with the metamagnetic behavior observed at
~T. In this regime, the development of a discrete inelastic
excitation in the neutron spectra indicates the appearance of spin dynamics
which are likely related to cooperative quantum fluctuations.Comment: 7 pages, 5 figures, 1 tabl
Chemically-Controlled Stacking of Inorganic Subnets in Coordination Networks: Metal-Organic Magnetic Multilayers
International audienceCoordination networks (CNs), such as, for instance, metal−organic frameworks (MOFs), can turn into remarkable magnets, with various topologies of spin carriers and unique opportunities of cross-coupling to other functionalities. Alternatively, distinct inorganic subnetworks that are spatially segregated by organic ligands can lead to coexisting magnetic systems in a single bulk material. Here, we present a system of two CNs of general formula Mn(H 2 O) x (OOC-(C 6 H 4) y-COO). The compound with two water molecules and one aromatic ring (x = 2; y = 1) has a single two-dimensional magnetic subnet, while the material with x = 1.5 and y = 2 shows, additionally, another type of magnetic layer. In analogy to magnetic multilayers that are deposited by physical methods, these materials can be regarded as metal−organic magnetic multilayers (MOMMs), where the stacking of different types of magnetic layers is controlled by the choice of an organic ligand during the chemical synthesis. This work further paves the way toward organic−inorganic nanostructures with functional magnetic properties
White Blood Cells in Patients Treated with Programmed Cell Death-1 Inhibitors for Non-small Cell Lung Cancer.
peer reviewedPURPOSE: To investigate whether eosinophils and other white blood cell subtypes could be used as response and prognostic markers to anti-Programmed cell Death-1 or anti-PD-Ligand-1 treatments in non-small cell lung cancer patients. METHODS: We retrospectively analyzed data from the NSCLC patients consecutively treated at our hospital with a PD-1/PD-L1 inhibitor in monotherapy for advanced disease. A total of 191 patients were evaluated at three time-points to investigate any relation between tumor response and WBC counts. RESULTS: Baseline WBC and subtypes did not differ according to the type of response seen under treatment. A higher relative eosinophil count (REC) correlated with more objective responses (p = 0.019 at t1 and p = 0.014 at t2; OR for progression = 0.54 and 0.53, respectively) independently of the smoking status, PD-L1 status, and immune-related toxicity (IRT). Higher REC was also associated with a longer duration of treatment (p = 0.0096). Baseline absolute neutrophil count was prognostic (p = 0.049). At t1 relative lymphocytes, absolute and relative neutrophils, and neutrophil-to-lymphocyte ratio were prognostic (p = 0.044, p = 0.014, p = 0.0033, and p = 0.029, respectively). CONCLUSION: Our results show that in NSCLC patients anti-PD-1/PD-L1 therapy induces an early increase only in blood eosinophils, more prominent in responding patients and independent of the smoking status, PD-L1 status, and IRT. Eosinophils are also associated with a longer duration of treatment. Furthermore, our data support a prognostic role of neutrophils, lymphocytes, and their ratio for NSCLC patients with advanced disease treated with PD(L)-1 blockade
Triple-sinusoid hedgehog lattice in a centrosymmetric Kondo metal
Superposed symmetry-equivalent magnetic ordering wave vectors can lead to
topologically non-trivial spin textures, such as magnetic skyrmions and
hedgehogs, and give rise to novel quantum phenomena due to fictitious magnetic
fields associated with a non-zero Berry curvature of these spin textures. To
date, all known spin textures are constructed through the superposition of
multiple spiral orders, where spins vary in directions with constant amplitude.
Recent theoretical studies have suggested that multiple sinusoidal orders,
where collinear spins vary in amplitude, can construct distinct topological
spin textures regarding chirality properties. However, such textures have yet
to be experimentally realised. In this work, we report the observation of a
zero-field magnetic hedgehog lattice from a superposition of triple sinusoidal
wave vectors in the magnetically frustrated Kondo lattice CePtAl4Ge2. Notably,
we also observe the emergence of anomalous electrical and thermodynamic
behaviours near the field-induced transition from the zero-field topological
hedgehog lattice to a non-topological sinusoidal state. These observations
highlight the role of Kondo coupling in stabilising the zero-field hedgehog
state in the Kondo lattice and warrant an expedited search for other
topological magnetic structures coupled with Kondo coupling
A facile method for the preparation of bifunctional Mn:ZnS/ZnS/Fe3O4 magnetic and fluorescent nanocrystals
Bifunctional magnetic and fluorescent core/shell/shell Mn:ZnS/ZnS/Fe3O4 nanocrystals were synthesized in a basic aqueous solution using 3-mercaptopropionic acid (MPA) as a capping ligand. The structural and optical properties of the heterostructures were characterized by X-ray diffraction (XRD), dynamic light scattering (DLS), transmission electron microscopy (TEM), UV–vis spectroscopy and photoluminescence (PL) spectroscopy. The PL spectra of Mn:ZnS/ZnS/Fe3O4 quantum dots (QDs) showed marked visible emission around 584 nm related to the 4T1 → 6A1 Mn2+ transition. The PL quantum yield (QY) and the remnant magnetization can be regulated by varying the thickness of the magnetic shell. The results showed that an increase in the thickness of the Fe3O4 magnetite layer around the Mn:ZnS/ZnS core reduced the PL QY but improved the magnetic properties of the composites. Nevertheless, a good compromise was achieved in order to maintain the dual modality of the nanocrystals, which may be promising candidates for various biological applications
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