Inelastic neutron scattering experiments reveal that the effective magnetic exchange couplings in NaFeAs are smaller and more isotropic than those in the heavily studied AFe2As2 family. These results provide evidence that the energy scale of the magnetic excitations, which are thought to influence the superconducting transition temperature, is controlled by the position of As atoms above the Fe layers.
Spin waves, measured using the ARCS chopper spectrometer at SNS, were studied in the antiferromagnetic ordered phase of NaFeAs, the parent compound of NaFe1−x CoxAs family of iron pnictide superconductors. NaFeAs was chosen because it has weak AF ordered moment, low superconducting transition temperature, and large As height, significantly different from AFe2As2.
C. Zhang, L.W. Harriger, Z. Yin, W. Lv, M. Wang, G. Tan, Y. Song, D. L. Abernathy, W. Tian, T. Egami, K. Haule, G. Kotliar, and P. Dai, “Effect of Pnictogen Height on Spin Waves in Iron Pnictides”. Phys. Rev. Lett. 112 (2014): 217202. http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.112.217202
This letter was submitted to Dr. Cherry A. Murray Director or Office of Science, US DOE. The letter expresses concern over the decline in the number of neutron facilities and urges DOE to prioritize plans for the Second Target Station at SNS and to fully utilize the existing beam ports at both SNS and HFIR. NSSA also offers its support and expertise in ongoing and future discussions related to DOE neutron scattering facilities.
The NSSA is pleased to announce the selection of the following 2016 NSSA Fellows: John Copley, Michael Crawford, Pengcheng Dai, Jaime Fernandez-Baca, Brent Fultz, Aaron Krawitz, Ramanan Krishnamoorti, Timothy Lodge, Jaroslaw Majewski, John Root, and Stephen White. Congratulations !
The NSSA is pleased to announce the 2016 NSSA prize winners:
Dr. Charles F. Majkrzak is the recipient of the Clifford G. Shull Prize,
Prof. Pengcheng Dai is the recipient Sustained Research Prize,
Dr. Yun Liu is the recipient of the Science Prize and
Dr. P. Douglas Godfrin is the recipient of the Prize for Outstanding Student Research.
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Join us for the 8th American Conference on Neutron Scattering (ACNS 2016). Held July 10-14, 2016 on board the historic Queen Mary in Long Beach, California, the Conference will provide essential information on the breadth and depth of current neutron-related research worldwide. Hosted by the Neutron Scattering Society of America, this year’s Conference will feature a combination of invited and contributed talks, poster sessions, tutorials and an industrial exhibit. Mark your calendar today and plan to attend ACNS 2016!
The American Crystallographic Association (ACA) has selected retired Laboratory Senior Fellow Benno Schoenborn, formerly of Bioenergy and Biome Sciences (B-11), to receive the 2016 Bau Neutron Diffraction Award. The Award recognizes exceptional research achievement in neutron diffraction. Schoenborn is honored for his pioneering research in macromolecular neutron crystallography and the design and development of the neutron crystallography beamline (Protein Crystallography Station, PCS) at the Los Alamos Neutron Scattering Center (LANSCE).
More detailed information can be found here.
NSSA was a sponsor for the Neutron Scattering Gordon Research Conference held in Hong Kong, June 21-26, 2015. The topic of the conference was “Effect of Disorder and Disordered Materials” and the conference web site can he found here. NSSA sponsorship primarily supported early career participation by US researchers attending the meeting.