Magnetic and transport properties of Ni/Ti, NiC/Ti and Co/Cu multilayers at high fields

Sdaq, A.; Broto, J.M.; Rakoto, H.; Ousset, J.C.; Raquet, Bertrand; Vidal, Bernard; Bobo, J.F.; Piécuch, M.; Baylac, B.

doi:10.1016/0304-8853(93)91233-w

Cited by 12 publications

(1 citation statement)

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“…The quality of the interface is strongly influenced by interdiffusion, intermixing and phase formation at the interface; it is therefore very interesting to investigate the role of various microstructural parameters at the interface. In this respect, while many structural and thermal stability studies on Ti/Ni MLs have been extensively reported in the literature [11][12][13][14][15], surprisingly few reports are available on corresponding magnetic [16][17][18][19][20][21] and electronic property [16,22] investigations. Recently, in our investigation carried out on annealed Ti/Ni MLs [16], we have reported a correlation study of structural, chemical and magnetic properties and it has been found that the Ti/Ni ML structures show amorphization in the temperature range of 300-400 • C. However, to the best of our knowledge no studies have been reported so far in the literature regarding the interface electronic property investigation of as-deposited as well as annealed Ti/Ni ML structures.…”

Section: Introductionmentioning

confidence: 99%

Investigation of interface electronic structure of annealed Ti/Ni multilayers

Bhatt¹,

Chaudhari²

2005

J. Phys.: Condens. Matter

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The present paper deals with a systemic investigation of the interface electronic structure of as-deposited as well as annealed Ti/Ni multilayer (ML) samples up to 400 °C using core level and valence band (VB) photoemission techniques. For this purpose [Ti(50 Å)/Ni(50 Å)] × 10 ML samples have been prepared by employing an electron beam evaporation technique under ultrahigh vacuum conditions.The depth profile core level photoemission investigation carried out on annealed ML samples indicates a gradual change in the nature of the electronic bonding at the interface with temperature. In particular the ML samples annealed at 300 and 400 °C clearly show shifts in the Ni 2p3/2 and Ti 2p3/2 core levels towards the higher binding energy side as compared to as-deposited samples, suggesting the formation of a TiNi alloy phase at the interface. The corresponding VB spectra also show appreciable changes and provide strong evidence for TiNi alloy formation. Further confirmation of this alloy phase formation is clearly reflected in the x-ray diffraction measurements carried out on these samples. The recorded x-ray diffraction patterns show a solid state reaction leading to amorphization when the ML sample is annealed at 300 °C and recrystallization to a TiNi alloy phase at the annealing temperature of 400 °C.In order to determine the charge transfer between Ti and Ni atoms in the formation of the TiNi alloy phase, the 2p3/2 core levels and the x-ray excited Auger regions of Ti and Ni were carefully investigated. The experimentally measured core level shifts for Ti and Ni were both found to be positive, leading to the conclusion that electronegativity criteria cannot be used to decide the direction of charge transfer in this case. The observed shifts in modified Auger parameters determined from recorded experimental data show a positive value for Ti and a negative one for Ni. This provides clear evidence that the direction of charge transfer is from Ni to Ti atoms during the formation of the TiNi alloy at the interface. The charge on ionized atoms calculated by using a simple electrostatic model indicates similar trends for the charge transfer deduced from Auger parameters and chemical shifts. In addition to this, areas under the core level peaks have been calculated by employing Shirley and Touggard background methods. The difference between the backgrounds, when normalized with respect to the elemental values, provides information about the density of states at the Fermi level (EF). The density of states at EF calculated in this way shows reductions in values for both Ti and Ni when the ML sample is annealed at different temperatures. This is in complete agreement with corresponding theoretically calculated densities of states.

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Section: Introductionmentioning

confidence: 99%

Investigation of interface electronic structure of annealed Ti/Ni multilayers

Bhatt¹,

Chaudhari²

2005

J. Phys.: Condens. Matter

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Magnetotransport in Metals and Alloys

Bass

2002

Characterization of Materials

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Electronic transport properties are fundamental to the classification of materials. The behaviors of the electrical resistivity ρ, the thermal conductivity κ, and the thermopower S are used to define whether a material is a metal, a semi‐conductor, or an insulator. Studies of how ρ, κ, and S vary with impurity content (alloying), magnetic field B , sample size, deformation, etc., provide insight into the nature of current carriers and how they are scattered. Studies of magnetoresistance, the variation of ρ with B , can yield additional information about electronic structure, the current carriers, and their scattering. In systems involving magnetic metals, has technical applications to magnetic sensing and memory. The Hall effect and the thermopower S can often be used to infer the sign of the charge of the majority current carriers, and the thermal conductivity κ, while closely related to ρ, can manifest differences that contain significant information. The Hall effect in semiconductors also finds use in sensors, but in metals it is smaller and usually of more interest for the physical insight it can provide into both nonmagnetic and magnetic metals. Changes with magnetic field in the thermal conductivity and thermoelectric coefficients of metals are usually small and difficult to measure. They have provided useful information about physical phenomena such as many‐body contributions to thermoelectricity and giant magnetoresistance in granular alloys and magnetic multilayers but are much less studied than the resistivity and Hall effect. Transport and magnetotransport measurements of metals and alloys are made over a wide range of temperatures extending from the lowest achievable temperature to the liquid state. This article focuses on four measured quantities in solid metals and alloys in the presence of a temporally constant and spatially uniform magnetic field B —the electrical resistance R , the Hall resistance , the thermal conductance K , and the thermopower S . The basic theory underlying these quantities applies also to liquid metals and alloys. The discussion begins with definitions and general information, including how to relate the measured quantities to the fundamental properties ρ, the Hall coefficient , κ, and S . These are followed by a brief description of the behaviors of ρ, κ, and S in zero magnetic field. Many more quantities than these four can be defined and measured, some of which have provided important information about metals. A few are briefly discussed.

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Magnetotransport in Metals and Alloys

Bass

2012

Characterization of Materials

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Electronic transport properties are fundamental to the classification of materials. The behaviors of the electrical resistivity ρ, the thermal conductivity κ, and the thermopower S are used to define whether a material is a metal, a semiconductor, or an insulator. Studies of how ρ, κ, and S vary with impurity content (alloying), magnetic field B , sample size, deformation, and so on, provide insight into the nature of current carriers and how they are scattered. Studies of magnetoresistance, the variation of ρ with B , can yield additional information about electronic structure, the current carriers, and their scattering. In systems involving magnetic metals, ρ( B ) has technical applications to magnetic sensing and memory. The Hall effect and the thermopower S can often be used to infer the sign of the charge of the majority current carriers, and the thermal conductivity κ, while closely related to ρ, can manifest differences that contain significant information. The Hall effect in semiconductors also finds use in sensors, but in metals it is smaller and usually of more interest for the physical insight it can provide into both nonmagnetic and magnetic metals. Changes with magnetic field in the thermal conductivity and thermoelectric coefficients of metals are usually small and difficult to measure. They have provided useful information about physical phenomena such as many‐body contributions to thermoelectricity and giant magnetoresistance in granular alloys and magnetic multilayers but are much less studied than the resistivity and Hall effect. Transport and magnetotransport measurements of metals and alloys are made over a wide range of temperatures extending from the lowest achievable temperature to the liquid state. This article focuses on four measured quantities in solid metals and alloys in the presence of a temporally constant and spatially uniform magnetic field B —the electrical resistance R , the Hall resistance R H , the thermal conductance K , and the thermopower S . The basic theory underlying these quantities applies also to liquid metals and alloys. The discussion begins with definitions and general information, including how to relate the measured quantities to the fundamental properties ρ, the Hall coefficient R 0 , κ, and S . These are followed by a brief description of the behaviors of ρ, κ, and S in zero magnetic field. Many more quantities than these four can be defined and measured, some of which have provided important information about metals. A few are briefly discussed.

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Magnetic and transport properties of Ni/Ti, NiC/Ti and Co/Cu multilayers at high fields

Cited by 12 publications

References 6 publications

Investigation of interface electronic structure of annealed Ti/Ni multilayers

Investigation of interface electronic structure of annealed Ti/Ni multilayers

Magnetotransport in Metals and Alloys

Magnetotransport in Metals and Alloys

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