Magnetic excitations in the weak itinerant ferromagnet MnSi

Abstract

Magnetic excitations in an intermetallic compound MnSi have been studied by neutron scattering. At 5 K in a magnetic field of 10 kOe, well-defined spin-wave excitations have been observed 0 belo~2.5 meV. The dispersion relation is almost isotropic and is hm"(meV) =0.13+52@2 (A 2) in the [100] direction, Above 3 meV, the excitation linewidth increases substantially, suggesting that the dispersion relation merges into the Stoner continuum. The Stoner excitations, which extend over almost all of the Brillouin zone, show a broad peak on the extension of the spin-wave dispersion relation. The spin-wave excitation renormalizes with increasing temperature and collapses into critical scattering above 40 K. On the other hand, the excitation in the Stoner continuum is aft'ected little by temperature; the excitations are qualitatively the same at T/T~=10 as at 5 K. The Stoner boundary energy decreases with increasing temperature. The results provide us with the first example of magnetic excitations in a weak itinerant ferromagnet.

Composition-dependent Magnetic Properties of Si1-xMnx(0.1 < x <0.9) Single Crystals

“…The magnetization of the crystals with 0.1 < x < 0.7 shows a transition at 30 K and decreases rapidly with increasing temperature. The obtained transition temperature of 30 K agrees well with the previous result for MnSi [6,7]. However, for x=0.75 and 0.82, the data show two distinct transitions at 70 K and 104 K. Fig.…”

“…Weak ferromagnetism appears in the solid solution between FeSi and CoSi [5]. MnSi in a zero magnetic field has a helical spin structure with a long period (180 Å) in the ordered state below a T C of about 29 K [6,7]. The helical spin state was observed to change into an induced ferromagnetic (FM) spin state by external magnetic fields.…”

A Manganese Ions Ground State in Mn&lt;sub&gt;x&lt;/sub&gt;Si&lt;sub&gt;1–x&lt;/sub&gt;: Negative- &lt;i&gt;U&lt;/i&gt; Properties Centre?

“…But, distances between the nearest ions of manganese in Mn 0.5 Si 0.5 , which do not form valence bonds with each other, practically coincides with such parameter for metallic γ-manganese [33].…”

“…Systematic measurements of the magnetic moment, located on the manganese ions, show presence of several temperature intervals in which magnetic ions demonstrate completely different properties [33] [34]. It is paramagnetic at temperature above 30 K. First-order transition takes place at 29.…”

Poslednie dostizheniya teorii magnetizma kollektivizirovannykh elektronov

“…И в самом деле, Ишикава и др. 83 провели недавно опыты по не-упругому рассеянию нейтронов на MnSi. Общие черты этих результатов сильно отличаются от тех, которые получены на Ni и Fe.…”