Itinerant Helimagnetic Single-Crystalline MnSi Nanowires

Abstract

We report the synthesis of free-standing MnSi nanowires via a vapor transport method with no catalyst and measurements of their electrical and magnetic properties for the first time. The single-crystalline MnSi nanowire ensemble with a simple cubic (B20) crystal structure shows itinerant helimagnetic properties with a T(c) of about 30 K. A single MnSi nanowire device was fabricated by a new method using photolithography and a nanomanipulator that produces good ohmic contacts. The single-nanowire device measurements provide large (20%) negative magnetoresistance and very low electrical resistivity of 544 microOmegacm for the MnSi nanowire.

Si-Based Magnetic Semiconductors

“…Nanostructures of transition metal silicides are being considered for spintronics applications for the same reasons expressed above for thin film geometries; they offer flexibility since both semiconducting and metallic magnetic ground states can be accessed without the complications of nonequilibrium growth conditions and related tendencies for second-phase nucleation and dopant clustering. A large number of transition metal monosilicide nanowires have been successfully grown including FeSi [160,161], CoSi [162,163], Fe 1Àx Co x Si [164,165], MnSi [166,167], NiSi, PtSi [168], and TiSi [168]. This list of materials is supplemented by a number of other transition metal silicide phases that have been synthesized in nanowire form including Ni 2 Si [169] [172,173]; TaSi 2 [168]; and Ti 5 Si 3 [168].…”

“…MnSi nanowires can also be grown using similar synthesis techniques; using MnCl 2 on Si substrate (SiO x ) produces nanowires 50-400 nm in diameter and as long as 100 mm [166,167]. The resistivity of these wires can be small (~50 mOcm in Ref.…”

Synthesis and Applications of Noble Metal and Metal Silicide and Germanide 1-Dimensional Nanostructures

“…[37][38][39] To fabricate a variety of single-crystalline metal silicide NWs, we employed CVT method where anhydrous metal halide beads and Si substrate or Si powder act as a metal source and a Si source, respectively. By using the CVT approach, we can synthesized not only many metal silicide NWs including MnSi, CrSi 2 , Fe 1-x Co x Si NWs, [40][41][42] but composition modulated cobalt silicides (CoSi, Co 2 Si, and Co 3 Si) 43 and iron silicides (FeSi and Fe 5 Si 3 ) NWs. 44 NT form of metal silicide (V 5 Si 3 NTs) was also synthesized.…”

“…51 To elucidate interesting physical phenomena of MnSi, which have not been clearly understood so far, making single-crystalline MnSi NWs is important because length scales of helimagnetic and skyrmion ordering of MnSi are intrinsically nanoscale. 40,52 Also, the MnSi NWs would provide opportunities for applications such as nanoscale magnetic refrigeration devices and nanospintronics. Free-standing MnSi NWs were grown on a Si substrate in the two-zone horizontal hot-wall furnace.…”

“…Free-standing MnSi NWs were grown on a Si substrate in the two-zone horizontal hot-wall furnace. 40 Si substrates played a dual role as a Si source and a substrate, and anhydrous MnCl 2 beads in an alumina boat were employed as a Mn source. SEM (Figure 22(a)) and TEM images (Figure 22(b)) show that NWs have a clean and smooth A single MnSi NW device as shown in Figure 23(a) was fabricated to investigate its electrical and MR properties.…”