Highlights

Initial test of the Diamond Anvil Cell (DAC) at HFIR HB-3A

Initial test of the Diamond Anvil Cell (DAC) at HFIR HB-3AWith an optimized region of interest, the background is ~ 10 cts/s. The data will be used to judge the feasibility of a future DAC experiment.

View the full presentation.



Circular-magnetic k-vector observed on a 0.02 mm3 crystal at HFIR HB-3A

Circular-magnetic k-vector observed on a 0.02 mm3 crystal at HFIR HB-3AThe circular distribution of k-vectors definitively confirms Fe3PO7 to have a “partially ordered” antiferromagnetic (AFM) helical state. One candidate for such a state is a short-range ordered AFM Skyrmion phase.

View the full presentation.



Orbital selective Mott transition observed in a quasi-1D Fe-based superconductor

Orbital selective Mott transition observed in a quasi-1D Fe-based superconductorNeutron diffraction has revealed that two iron based ladder compounds, CsFe2Se3 and BaFe2S3, exhibit highly contrasting responses to hydraulic pressure despite their identical crystal structure and similar magnetic structures. The magnetic order in CsFe2Se3 stays unchanged up to 2 GPa, while that in BaFe2S3 undergoes a rather abrupt enhancement around 1 GPa both in transition temperature and ordered moment. Such unusual change bear the signature of an orbital-selective Mott transition.

View the full presentation.


New magnetoelectric mechanism in a chiral-lattice antiferromagnet

New magnetoelectric mechanism in a chiral-lattice antiferromagnetNeutron scattering has shown that the spin-texture chirality in the chiral-lattice antiferromagnet MnSb2O6 is preserved when the electric polarization is reversed by the application of an external magnetic field.

View the full presentation.




A New Direction for Iron-Based Superconductors

A New Direction for Iron-Based Superconductors Single-crystal neutron diffraction is a powerful means of determining magnetic structures, and here it is used to show the parent phase of superconductors in the KxFe2-ySe2 family has a novel magnetically ordered semiconducting ground state.

View the full presentation.




Controlling Magnetic Order by Chemical Compression

Controlling Magnetic Order by Chemical CompressionMagnetic properties of Ca1–xEuxCo2As2 vary from itinerant (3d) antiferromagnetism of Co in CaCo2As2 to the combination of itinerant (3d, Co) and localized (4f, Eu) ferromagnetism in the intermediate range to localized (4f) antiferromagnetism in Eu-rich samples.

View the full presentation.



Localized to Strongly Correlated Electron Transition in EuCo2As2

Localized to Strongly Correlated Electron Transition in EuCo2As2A combination of neutron diffraction, x-ray diffraction, and heat capacity measurements in conjunction with first principles calculations were used to show that the LaCu6-xAux system hosts the first known example of an elastic quantum critical point. Neutron and x-ray diffraction measurements were performed to study the structural properties as a function of temperature and Au-composition. First principle calculations confirm that the phase transition is driven by an elastic instability and is independent of electronic properties. Heat capacity measurements indicate the presence of quantum fluctuations at the critical composition.

View the full presentation.


Candidate Elastic Quantum Critical Point in LaCu6-xAux

Candidate Elastic Quantum Critical Point in LaCu6-xAuxA combination of neutron diffraction, x-ray diffraction, and heat capacity measurements in conjunction with first principles calculations were used to show that the LaCu6-xAux system hosts the first known example of an elastic quantum critical point. Neutron and x-ray diffraction measurements were performed to study the structural properties as a function of temperature and Au-composition. First principle calculations confirm that the phase transition is driven by an elastic instability and is independent of electronic properties. Heat capacity measurements indicate the presence of quantum fluctuations at the critical composition.

View the full presentation.


Spin Reorientation in TlFe1.6Se2 with Complete Vacancy Ordering

Spin Reorientation in TlFe1.6Se2 with Complete Vacancy OrderingA combination of neutron diffraction, x-ray diffraction, and heat capacity measurements in conjunction with first principles calculations were used to show that the LaCu6-xAux system hosts the first known example of an elastic quantum critical point. Neutron and x-ray diffraction measurements were performed to study the structural properties as a function of temperature and Au-composition. First principle calculations confirm that the phase transition is driven by an elastic instability and is independent of electronic properties. Heat capacity measurements indicate the presence of quantum fluctuations at the critical composition.

View the full presentation.


Spin Reorientation and Magnetism in Yb14-xPrxMnSb11

Spin Reorientation and Magnetism in Yb14-xPrxMnSb11An abnormal peak is observed in the dc magnetic susceptibility of Yb13.47Pr0.53MnSb11. Neutron diffraction clearly indicates that this peak is caused by a spin re-orientation of Mn moments, which is consistent with results of magnetization measurements. Refinement on the data collection also shows that moments on Mn are ordered and that moments on Pr are not.

View the full presentation.



Polarized Neutron Diffraction at HFIR HB-3A

Polarized Neutron Diffraction at HFIR HB-3AHigh neutron polarization ratio (>94%) and a good transmission (16% based on the diffraction on a 2 mm size hexaferrite crystal) enable effective polarized neutron diffraction at HB-3A. Tolerance to the horizontal focus yields double the neutron flux. 24% transmission can be achieved by moving the polarizer closer to the sample position, which requires redesigning a more compact flipper and collimator mount.

View the full presentation.


Weak Itinerant Ferromagnetism Detected by Polarized Neutron Diffraction

Weak Itinerant Ferromagnetism Detected by Polarized Neutron DiffractionHigh neutron polarization ratio (>95%) has been achieved at the HFIR HB-3A single crystal neutron diffractometer. This is the first use of this capability on an experiment approved through the General User program. We succeeded in detecting a weak itinerant ferromagnetic moment of 0.11(1)μB/atom on a NiCoCr0.6 crystal with an effective mass of 20 mg.

View the full presentation.



The ordered low-dimensional frustrated magnets challenge the nonlinear spin-wave theories

The ordered low-dimensional frustrated magnets challenge the nonlinear spin-wave theoriesResults on an ordered low dimensional frustrated magnet suggest a new theoretical framework is needed for adequate description.

View the full presentation.




SPICE upgrade for HB-3A 2D detector

SPICE upgrade for HB-3AAdded cursors to identify each pixel ID, corresponding hkl, and received neutron counts. New function to let users define Region of Interests. Instrument configuration is written in each measured data. Improved capability for optimizing the data collections. Monitor was better synchronized through HFIRLITE

View the full presentation.




Itinerant Antiferromagnetism in RuO2

Itinerant Antiferromagnetism in RuO2Rutile-type RuO2 had been considered a Pauli paramagnet, until this report demonstrated a previously undetected lattice distortion below approximately 900 K accompanied by antiferromagnetic order. The room temperature magnetic moment of approximately 0.05 μB is small, but clearly confirmed by polarized neutron diffraction. This experiment and corresponding theory suggest that the combination of high Néel temperature and small itinerant moments in RuO2 are unique among metallic oxides.

View the full presentation.