<sup>3</sup>He spin filters for spherical neutron polarimetry at the hot neutrons single crystal diffractometer POLI-HEiDi

Hutanu, Vladimir; Meven, Martin; Masalovich, S.; Heger, G.; Roth, Georg

doi:10.1088/1742-6596/294/1/012012

Cited by 29 publications

(29 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Determination of and correction for the time-dependence of the 3 He spin filters was performed as established in Ref. [37]. Diffraction scans were performed at 0.4 K, well below the order parameter saturation temperature of ~2 K. In both panels of Fig.…”

Section: Resultsmentioning

confidence: 99%

Low temperature magnetic structure of CeRhIn₅by neutron diffraction on absorption-optimized samples

Fobes

Bauer

Thompson

et al. 2017

J. Phys.: Condens. Matter

Self Cite

View full text Add to dashboard Cite

Abstract. Two aspects of the ambient pressure magnetic structure of heavy fermion material CeRhIn 5 have remained under some debate since its discovery: whether the structure is indeed an incommensurate helix or a spin density wave, and what is the precise magnitude of the ordered magnetic moment. By using a single crystal sample optimized for hot neutrons to minimize neutron absorption by Rh and In, here we report an ordered moment of = 0.54(2) + . In addition, by using spherical neutron polarimetry measurements on a similar single crystal sample, we have confirmed the helical nature of the magnetic structure, and identified a single chiral domain. IntroductionThe Doniach phase diagram explores a competition in energy scales common to heavy fermion materials, between the Ruderman-Kittel-Kasuya-Yosida (RKKY) and Kondo interactions, which scale as ~. and ~0 1/3 , respectively, where J is the dimensionless Kondo coupling constant [1]. On one side of the phase diagram exists localized magnetism due to RKKY and on the other a totally Kondo-quenched paramagnetic state. Perhaps the most interesting scenarios are those in the middle of the phase diagram where the Kondo and RKKY energy scales are comparable. To find systems of this nature it is imperative to accurately measure these energy scales. CeRhIn 5 is one such system where these scales are believed to be competing.The temperature-pressure phase diagram of CeRhIn 5 is prototypical for heavy fermion materials; at ambient pressure, it displays incommensurate antiferromagnetic (AFM) order below T N = 3.8 K, and with increasing applied pressure T N is suppressed to a quantum critical point at P c = 2.25 GPa around which a broad dome of unconventional superconductivity emerges [2][3][4][5]. In detail, however, the properties of the AFM ground state in CeRhIn 5 deviate from prototypical behavior. Namely, the ground state magnetic order was reported to be helical, rather than spin-density-wave-type (SDW) by neutron measurements [2] and was later confirmed by 115 In NQR measurements [6,7]. Notably, the Ce magnetic moments were found to lie in the tetragonal ab-plane with the helix propagating along c [8]. Recent neutron spectroscopy measurements observed a small energy gap Δ = 0.25 meV in the spin wave spectra of the AFM state [9], but in the absence of magnetic anisotropies in the plane containing the spiraling spins a gapless Goldstone mode is expected for an incommensurate helical magnetic structure. Although an in-plane interaction invariant under the C 4 symmetry of the tetragonal structure may be possible, the gapless Goldstone mode is protected by translational symmetry of the magnetic helix along c. In principle, a sufficiently strong C 4 magnetic anisotropy (comparable to the exchange interactions along c), would distort the magnetic helix and break the associated translational symmetry, resulting in the formation of a spin gap. However, distortion of the helix would also lead to higher harmonic diffraction peaks, which have never been

show abstract

Section: Resultsmentioning

confidence: 99%

Low temperature magnetic structure of CeRhIn₅by neutron diffraction on absorption-optimized samples

Fobes

Bauer

Thompson

et al. 2017

J. Phys.: Condens. Matter

Self Cite

View full text Add to dashboard Cite

show abstract

“…SNP measurements were performed at 4 K with a Cryopad on the polarized single-crystal diffractometer POLI@HEiDi at the hot source of the FRM II reactor in Garching, Germany [19,20]. A Ge (311) monochromator was used to generate a monochromatic neutron beam with 1.17Å wavelength.…”

Section: Methodsmentioning

confidence: 99%

“…Polarization corrections described in detail in Ref. [20] were applied. With this method 1% precision on polarization matrix elements can be reliably reached [20].…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

et al. 2014

View full text Add to dashboard Cite

We report on spherical neutron polarimetry and unpolarized neutron diffraction in zero magnetic field as well as flipping ratio and static magnetization measurements in high magnetic fields on the multiferroic square lattice antiferromagnet Ba 2 CoGe 2 O 7 . We found that in zero magnetic field the magnetic space group is Cm m2 with sublattice magnetization parallel to the [100] axis of this orthorhombic setting. The spin canting has been found to be smaller than 0.2 • in the ground state. This assignment is in agreement with the field-induced changes of the magnetic domain structure below 40 mT as resolved by spherical neutron polarimetry. The magnitude of the ordered moment has been precisely determined. Above the magnetic ordering temperature short-range magnetic fluctuations are observed. Based on the high-field magnetization data, we refined the parameters of the recently proposed microscopic spin model describing the multiferroic phase of Ba 2 CoGe 2 O 7 .

show abstract

“…The neutrons were polarized using specially designed 3 He gas cells [16]. The same type of cell was also used as analyzer for measuring beam polarization.…”

Section: Methodsmentioning

confidence: 99%

Measurement of the ROT effect in the neutron induced fission of ²³⁵U in the 0.3 eV resonance at a hot source of polarized neutrons

et al. 2018

View full text Add to dashboard Cite

Abstract. The TRI and ROT asymmetries in fission of heavy nuclei have been extensively studied during more than a decade. The effects were first discovered in the ternary fission in a series of experiments performed at the ILL reactor (Grenoble) by a collaboration of Russian and European institutes, and were carefully measured for a number of fissioning nuclei. Later on, the ROT effect has been observed in the emission of prompt gamma rays and neutrons in fission of 235 U and 233 U, although its value was an order of magnitude smaller than in the α-particle emission from ternary fission. All experiments performed so far are done with cold polarized neutrons, what assumes a mixture of several spin states, the weights of these states being not well known. The present paper describes the first attempt to get "clean" data by performing the measurement of gamma and neutron asymmetries in an isolated resonance of 235 U at the POLI instrument of the FRM2 reactor in Garching.

show abstract

³He spin filters for spherical neutron polarimetry at the hot neutrons single crystal diffractometer POLI-HEiDi

Cited by 29 publications

References 12 publications

Low temperature magnetic structure of CeRhIn₅by neutron diffraction on absorption-optimized samples

Low temperature magnetic structure of CeRhIn₅by neutron diffraction on absorption-optimized samples

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

Measurement of the ROT effect in the neutron induced fission of ²³⁵U in the 0.3 eV resonance at a hot source of polarized neutrons

Contact Info

Product

Resources

About

3He spin filters for spherical neutron polarimetry at the hot neutrons single crystal diffractometer POLI-HEiDi

Cited by 29 publications

References 12 publications

Low temperature magnetic structure of CeRhIn5by neutron diffraction on absorption-optimized samples

Low temperature magnetic structure of CeRhIn5by neutron diffraction on absorption-optimized samples

Evolution of two-dimensional antiferromagnetism with temperature and magnetic field in multiferroicBa2CoGe2O7

Measurement of the ROT effect in the neutron induced fission of 235U in the 0.3 eV resonance at a hot source of polarized neutrons

Contact Info

Product

Resources

About

³He spin filters for spherical neutron polarimetry at the hot neutrons single crystal diffractometer POLI-HEiDi

Low temperature magnetic structure of CeRhIn₅by neutron diffraction on absorption-optimized samples

Low temperature magnetic structure of CeRhIn₅by neutron diffraction on absorption-optimized samples

Measurement of the ROT effect in the neutron induced fission of ²³⁵U in the 0.3 eV resonance at a hot source of polarized neutrons