Experimental methods for the determination of magnetic, electrical and thermal transport properties of condensed matter

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Experimental methods for the determination of
magnetic, electrical and thermal transport
properties of condensed matter
Janez Dolinšek FMF Uni-Ljubljana J. Stefan
Institute, Ljubljana
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Magnetic, electrical and thermal transport
properties

• Magnetic susceptibility
• Electrical resistivity
• Thermoelectric power
• Hall coefficient
• Thermal conductivity

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Introduction

• Why to measure magnetic, electrical and thermal
  transport properties of solid materials ?
• Ever-present demand for new materials with
  novel/improved physical-chemical-mechanical
  properties
• Novel materials preparation techniques were
  developed
• High-quality single crystals available
• Complex metallic alloys (CMAs) and quasicrystals
  (QCs) offer unique physical properties or
  combinations of properties
• Electrical conductor thermal insulator
• Combination of hardness elasticity small
  friction coefficient
• Potential applications in high technology

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Complex Metallic Alloys

• Intermetallic compounds
• Giant unit cells
• Cluster arrangement of atoms
• Inherent disorder
• Con?gurational
• Chemical or substitutional
• Partial or split occupation

quasicrystals 8 YbCu4.5 7448 at. / u.
c. ?-Al-Pd-Mn 1480 at. / u. c. ß-Al3Mg2 1168
at. / u. c. ?-Al4Mn 586 at. / u.
c. Al39Fe2Pd21 248 at. / u. c. Mg32(Al,Zn)49 162
at. / u. c. Re14Al57 71 at. / u.
c. elem. metals lt5 at. / u. c.
Mg32(Al,Zn)49
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Quasicrystals

• Discovered in1984
• Thermodynamically stable samples have appeared
  after 1990
• Well-ordered but nonperiodic solids
• Diffraction patterns with non-crystallographic
  point symmetry

Diffraction pattern of a decagonal quasicrystal
Penrose tiling (quasiperiodic)
Periodic tiling
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Sample preparation
Czochralski method
Bridgman method
Flux-grown method

• The first solidification zone
• Coexistence of solid and liquid phases

Single-crystal is cut in bar-shaped samples
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Al-Co-Ni decagonal QC
Czochralski method
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Experimental methods
Magnetization and magnetic susceptibility
measurement
magnetic susceptibility
SQUID magnetometer 5 T
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Experimental methods
Measurement of the electrical conductivity
Electrical resistance R U/I
PPMS Physical Property Measurement System 9 T
Specific resistivity
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Experimental methods
Thermoelectric effect
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Experimental methods
Measurement of the thermoelectric power
Thermal conductivity measurement
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Experimental methods
Measurement of the Hall coefficient
Hall coefficient
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Magnetization vs. magnetic field
o-Al13Co4
Y-Al-Ni-Co
FM contribution
linear term
i-Al64Cu23Fe13
Al4(Cr,Fe)
ferromagnetic component
linear term
Curie magnetizations
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Magnetic susceptibility
Y-Al-Ni-Co
i-Al64Cu23Fe13
temperature-independent term
Curie-Weiss susceptibility
temperature-dependent correction
o-Al13Co4
Al4(Cr,Fe)
temperature-independent term
Curie-Weiss susceptibility
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Electrical resistivity
o-Al13Co4
Y-Al-Ni-Co
PTC of the resistivity predominant role of
electron-phonon scattering mechanism
(Boltzmann type)
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Electrical resistivity
Al4(Cr,Fe)
i-Al64Cu23Fe13
r is nonmetallic with NTC
slow charge carriers
pseudogap in s(e)
specific distribution of Fe
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Thermoelectric power
Y-Al-Ni-Co
o-Al13Co4
Al4(Cr,Fe)
i-Al64Cu23Fe13
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Hall coefficient

• RH values of QCs and CMAs are typical metallic
• RHs exhibits pronounced anisotropy
• Fermi surface is strongly anisotropic
• consists of hole-like and electron-like parts

Y-Al-Ni-Co
o-Al13Co4
Al4(Cr,Fe)
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Thermal conductivity

• Total k is a sum of the electronic kel and the
  phononic kph contribution
• kel is estimated from the Wiedemann-Franz law
  kelp2kB2Ts(T)/3e2
• WF law valid when elastic scattering of
  electrons is dominant

Al4(Cr,Fe)
Y-Al-Ni-Co
o-Al13Co4
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Thermal conductivity
i-Al64Cu23Fe13
hopping of localized vibrations
electronic part
long wave phonons (Debye model)

• k300K lt 1.7 W/mK lower than SiO2 (2.8 W/mK)

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Thank you for your attention !