Weak Antiferromagnetism in NbFe₂

Spectroscopic evidence for strong quantum spin fluctuations with itinerant character inYFe2Ge2

“…This indicates that, as for the pnictide Fe-HTSC, the value ≈ 1 μ B extracted with PES is an estimate of the averaged magnitude of fast-fluctuating spin moments on the Fe sites. As for the Fe-HTSC, the best fits to the Fe 3s spectra are always obtained when the curve fitting the peak at higher BE is mainly of Gaussian character, with a width much larger than that of the lower BE peak and that expected from [ 38,39,40].…”

Quantum criticality in NbFe2induced by zero carrier velocity

“…[2][3][4] Nb 1−x Fe 2+x is a rare example of an itinerant transition metal intermetallic compound displaying antiferromagnetic quantum criticality. Its unusual magnetic behavior and its sensitivity to off-stoichiometry (Nb deficiency x) has been known for over two decades, 5,6 and its phase diagram and low temperature (T), small x behavior has recently been clarified. [7][8][9] At stoichiometry, its susceptibility is Curie-Weiss-like down to the SDW transition (probably long wavelength) at T sdw =10 K with vanishing Curie-Weiss temperature, reflecting antiferromagnetism (AF) in close proximity to a FM QCP.…”

Spectroscopic study of metallic magnetism in single-crystallineNb1−yFe2+y

“…In the Nb 1−y Fe 2+y composition series, the magnetic state depends sensitively on composition [8][9][10][11] . Nbrich (y < −0.02) and Fe-rich (y > 0.005) Nb 1−y Fe 2+y are weakly ferromagnetic (FM) at low temperature, which may be attributed to changes in the electronic structure [12][13][14][15] .…”

“…Despite many experimental efforts, microscopic evidence for the existence of a broken symmetry magnetic low temperature state in stoichiometric NbFe 2 has so far been lacking. NMR studies on polycrystals 9 require magnetic fields exceeding the critical field of the ordered phase for some grain orientations, whereas the small size of the ordered moment, estimated to less than 0.1µ B /Fe from magnetization measurements in the FM state, imply a tiny signal size in neutron scattering. Here, we present low temperature electron spin resonance (ESR), muon spin relaxation (µSR) and Mössbauer spectroscopy experiments on single and polycrystalline Nb 1−y Fe 2+y in the alloying range −0.004 ≤ y ≤ 0.018, thus covering the range from SDW to FM ground state.…”