Structural and magnetic properties of Mn5Ge3 clusters in a dilute magnetic germanium matrix

Bihler, C.; Jaeger, Carsten; Vallaitis, T.; Gjukic, M.; Brandt, Martin S.; Pippel, Eckhard; Woltersdorf, J.; Gösele, U.

doi:10.1063/1.2185448

Cited by 131 publications

(118 citation statements)

References 22 publications

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“…[20] In the sample with x ≈ 0.03 discussed in detail there, reported on in Ref. [20] (T S = 225 • C), the average Mn 5 Ge 3 cluster diameter ≈ 15 nm in Ref.…”

Section: Resultsmentioning

confidence: 99%

“…[20] In the sample with x ≈ 0.03 discussed in detail there, reported on in Ref. [20] (T S = 225 • C), the average Mn 5 Ge 3 cluster diameter ≈ 15 nm in Ref. [20] can be regarded as an upper limit for sample Ge 0.96 Mn 0.04 , which lies well below typical values for the critical diameter below which each cluster is expected to exhibit a single domain (≈ 15 to 30 nm).…”

Section: Resultsmentioning

confidence: 99%

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Spin-glass-like behavior of Ge:Mn

Jaeger

Bihler²,

Vallaitis³

et al. 2006

Phys. Rev. B

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We present a detailed study of the magnetic properties of low-temperature molecular beam epitaxy grown Ge:Mn dilute magnetic semiconductor films. We find strong indications for a frozen state of Ge 1−x Mn x , with freezing temperatures of T f = 12 K and T f = 15 K for samples with x = 0.04 and x = 0.2, respectively, determined from the difference between field cooled and zero-field cooled magnetization. For Ge 0.96 Mn 0.04 , AC susceptibility measurements show a peak around T f , with the peak position T ′ f shifting as a function of the driving frequency f by ∆T ′ f /[T ′ f · ∆logf ] ≈ 0.06, whereas for sample Ge 0.8 Mn 0.2 a more complicated behavior is observed. Furthermore, both samples exhibit relaxation effects of the magnetization after switching the magnitude of the external magnetic field below T f which are in qualitative agreement with the field and zero-field cooled magnetization measurements. These findings consistently show that Ge:Mn exhibits a frozen magnetic state at low temperatures, and that it is not a conventional ferromagnet.

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“…[20] In the sample with x ≈ 0.03 discussed in detail there, reported on in Ref. [20] (T S = 225 • C), the average Mn 5 Ge 3 cluster diameter ≈ 15 nm in Ref.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Spin-glass-like behavior of Ge:Mn

Jaeger

Bihler²,

Vallaitis³

et al. 2006

Phys. Rev. B

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“…Bulk thin intermetallic films have been observed on Ge(111), 2 while phase separation was found on a µm scale in single crystals 1 and on a sub-µm scale in MBE fabricated samples. 9 Since the Mn content in ferromagnetic GeMn intermetallic compounds is of the order of 60% and above, 10 compound formation will result in large magnetic moments and a strong influence on the magnetic properties of the system even if the compounds form on a nanometer scale. An identification of intermetallic compounds in structural analysis therefore facilitates the interpretation of the magnetic properties of GeMn films.…”

Section: Introductionmentioning

confidence: 99%

“…Various fabrication techniques have recently been employed to realise GeMn magnetic semiconductors, including single crystal growth, 1 solid phase epitaxy 2 and molecular beam epitaxy (MBE). 3,4,5,6,7,8,9 Irrespective of the fabrication technique, the formation of ferromagnetic, intermetallic compounds can occur. Bulk thin intermetallic films have been observed on Ge(111), 2 while phase separation was found on a µm scale in single crystals 1 and on a sub-µm scale in MBE fabricated samples.…”

Section: Introductionmentioning

confidence: 99%

Magnetic and structural properties ofGexMn1−xfilms: Precipitation of intermetallic nanomagnets

et al. 2006

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We present a comprehensive study relating the nanostructure of Ge0.95Mn0.05 films to their magnetic properties. The formation of ferromagnetic nanometer sized inclusions in a defect free Ge matrix fabricated by low temperature molecular beam epitaxy is observed down to substrate temperatures TS as low as 70 • C. A combined transmission electron microscopy (TEM) and electron energy-loss spectroscopy (EELS) analysis of the films identifies the inclusions as precipitates of the ferromagnetic compound Mn5Ge3. The volume and amount of these precipitates decreases with decreasing TS. Magnetometry of the films containing precipitates reveals distinct temperature ranges: Between the characteristic ferromagnetic transition temperature of Mn5Ge3 at approximately room temperature and a lower, TS dependent blocking temperature TB the magnetic properties are dominated by superparamagnetism of the Mn5Ge3 precipitates. Below TB, the magnetic signature of ferromagnetic precipitates with blocked magnetic moments is observed. At the lowest temperatures, the films show features characteristic for a metastable state.

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“…1 For this reason, Ge-based ͑such as GeMn͒ diluted magnetic semiconductors ͑DMSs͒, compatible with the current Si technology, have been studied extensively. [2][3][4][5][6][7][8][9][10][11][12][13] It is well understood that the low solubility of Mn in Ge has been a main barrier to achieve a high T c DMS GeMn film with high Mn concentration and uniformly distributed Mn in Ge. As a consequence, Mn-rich precipitates, such as Mn 5 Ge 3 , 9,14,15 Mn 5 Ge 2 , and Mn 11 Ge 8 , 12 are usually observed and are believed to be responsible for the observed ferromagnetism up to room temperature.…”

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confidence: 99%

Tadpole shaped Ge0.96Mn0.04 magnetic semiconductors grown on Si

Wang

Xiu

Zou

et al. 2010

Applied Physics Letters

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Magnetic and structural properties of a Ge0.96Mn0.04 thin film grown on Si has been investigated by transmission electron microscopy and superconducting quantum interference device. Tadpole shaped coherent GeMn clusters induced by spinodal decomposition were revealed in the film. Although these coherent clusters are dominant, Mn5Ge3 precipitates can be still detectable, contributing to a complex ferromagnetism. The Ge buffer layer, by relieving the misfit strain between Si and Ge, can significantly reduce the density of lattice defects in the subsequent GeMn layer. Our findings unveil a particular morphology of GeMn clusters, which would contribute to better understand the GeMn system.

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Structural and magnetic properties of Mn5Ge3 clusters in a dilute magnetic germanium matrix

Cited by 131 publications

References 22 publications

Spin-glass-like behavior of Ge:Mn

Spin-glass-like behavior of Ge:Mn

Magnetic and structural properties ofGexMn1−xfilms: Precipitation of intermetallic nanomagnets

Tadpole shaped Ge0.96Mn0.04 magnetic semiconductors grown on Si

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