| 1. |
- Stenström, Bengt, et al.
(author)
-
Magnetoresistance of Hexagonal FeGe Single Crystals between 4.2 K and 30 K
- 1972
-
In: Physica scripta. T. - : IOP Publishing. - 0281-1847 .- 0031-8949 .- 1402-4896. ; 6:2-3, s. 164-168
-
Journal article (peer-reviewed)abstract
- The low field transverse magnetoresistance of hexagonal FeGe has been measured for the field in the basal plane with current both parallel and perpendicular to the c-axis. At a temperature dependent critical field (Δ/0) // c shows a sharp peak, then decreases rapidly until it levels off at a second critical field. (Δ/0) ⊥ c exhibits a sharp dip at the first critical field followed by rising magnetoresistance with increasing field until the second critical field, where it levels off. The observed anomalies are related to changes in the spin structure and magnetic superzone effects. The possibilities of itinerant antiferromagnetism are also considered.
|
|
| 2. |
- Stenström, Bengt, et al.
(author)
-
The Electrical Resistivity of Hexagonal FeGe Single Crystals
- 1972
-
In: Physica scripta. T. - : IOP Publishing. - 0281-1847 .- 0031-8949 .- 1402-4896. ; 6:4, s. 209-213
-
Journal article (peer-reviewed)abstract
- Electrical resistivity measurements have been carried out on hexagonal FeGe (B 35), which is a uniaxial antiferromagnet with TN=411 K. The resistivity parallel to the c-axis exhibits a hump below TN, which arises from the magnetic superzones cutting and distorting different contributions to the Fermi surface. For the current in the basal plane a mere change in slope is observed in the resistivity at the Néel temperature. Critical scattering, as well as imperfections, tend to smooth out the transition behaviour and an attempt is made to determine the critical exponent in d/dT = Cε-λ, where ε = |T-TN|/TN. For current parallel to the c-axis λ ≈ 0.8 for T>TN and λ ≈ -0.4 for T<TN. The case of resistivity perpendicular to the c-axis is less amenable to detailed analysis. The strong ferromagnetic ordering in the basal plane gives rise to long-range spin fluctuations, while the weak antiferromagnetic interactions along the c-axis give mainly short-range fluctuations above TN.
|
|
| 3. |
- Sundström, Lorna J.
(author)
-
Fermi Surface, Electrical Resistivity and Magnetic Ordering of Antiferromagnetic Hexagonal FeGe
- 1972
-
In: Physica scripta. T. - : IOP Publishing. - 0281-1847 .- 0031-8949 .- 1402-4896. ; 6:2-3, s. 158-163
-
Journal article (peer-reviewed)abstract
- Nonrelativistic APW calculations of the electronic energy bands of hexagonal (B 35) iron monogermanide (FeGe) have recently been published [15]. The present work extends these to determine the Fermi surface, which is formed from four energy bands. Large portions of the Fermi surface will be destroyed or distorted by magnetic superzones at the onset of antiferromagnetic ordering (TN = 411 K). This is related to experimental resistivity measurements, which show a distinct anomaly at the Néel temperature. We find that "nesting" of Fermi hole and electron surfaces might give rise to a broad maximum in the generalized susceptibility around q = π/c. Further aspects of the role of the Fermi surface in magnetic ordering are briefly discussed.
|
|
