Amar Srivastava - Academia.edu (original) (raw)

Papers by Amar Srivastava

I particularly want to thank Dr. Helene Rotella who joined NanoCore when I was in my last year of... more I particularly want to thank Dr. Helene Rotella who joined NanoCore when I was in my last year of Ph.D. Her experimental expertise and analytical skills have improved my understanding on my research work. I cannot be thankful enough to her for encouraging me and giving me moral support during the most difficult times while writing this thesis. Finally and most importantly, I want to express my love and gratitude to family members. My parents, brother Gaurav, sisters Garima and Pooja-you are the source of my sustenance. I could not have asked for anything more from you. It is all because of you. Thank you for being so patient and supportive especially during the time of my

Scientific reports, Nov 15, 2016

Here, we report the presence of defect-related states with magnetic degrees of freedom in crystal... more Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for ...

Understanding and manipulating the spin-orbit coupling (SOC) in electronic systems is important f... more Understanding and manipulating the spin-orbit coupling (SOC) in electronic systems is important for spintronics devices and also for the fundamental phenomena such as triplet state superconductivity, topological insulators and Majorana fermions which are forefront topics in condensed matter physics today. In this experimental paper, we report gate tunable anisotropic Rashba spin-orbit coupling (SOC) at LaAlO3/SrTiO3(110) interface with a large spin splitting energy of 25 meV as compared to semiconductor heterostructures. The anisotropy in SOC is understood to arise from the difference in electron effective mass along [001] and [1-10]. Samples of two different LaAlO3 thicknesses were chosen to study the effect of strain, z-confinement, band filling and crystal orientation on SOC. We see a clear evidence of gate tunable out-of-plane SOC in addition to the usual in-plane SOC due to a broken symmetry in the plane of the interface and its relative contribution is determined by the extent of z-confinement. Our study clearly shows that the orbital occupancy and the strength of SOC are not explicitly related.

Physical Review B, 2015

Vanadium dioxide (VO 2) undergoes an unusual insulator-metal transition (IMT), and after decades ... more Vanadium dioxide (VO 2) undergoes an unusual insulator-metal transition (IMT), and after decades of study, the origin of the IMT remains hotly debated. Here, by analyzing spectral-weight transfers (SWTs) of x-ray absorption spectroscopy at the V L 3,2 and O K edges on specially designed VO 2 films, we observe d || (d x 2 −y 2) band splitting at the V L 3,2 edges across the IMT, accompanied by anomalous SWTs as high as ∼12 eV at the O K edge, indicating strong electronic correlations. Surprisingly, a few oxygen vacancies induce dramatic SWTs at the O K edge, but the sample remains conducting. Supported by theoretical calculations, we find that in the metallic state, direct V(3d)-V(3d) and O(2p)-V(3d) hybridized orbital correlations are screened by O(2p)-V(3d π) hybridized orbitals, while in the insulating state they are strongly correlated due to changes in the oxygen orbital occupancy. Our result shows the importance of screenings and electronic correlations for IMTs in VO 2 .

117576-We show that Ti 0.94 M 0.06 O 2 (M = Nb, Ta) thin films are Kondo systems by angle depende... more 117576-We show that Ti 0.94 M 0.06 O 2 (M = Nb, Ta) thin films are Kondo systems by angle dependent magneto-resistance measurement. Surprisingly, the data fitted by both Goldhaber-Gordon and Hamann formula yield comparable carrier dependent Kondo temperatures (10-60 K). The Kondo temperature dependence on carrier density was different for Ta and Nb incorporated in TiO 2 but this result could be understood on the basis of the formation of compensating defects (Ti vacancies) which also act as localized magnetic scattering centers. Using the unitarity-limit resistivity and Kondo temperature estimated from these fits the normalized resistivity versus temperature for all these films collapse into a universal curve consistent with data observed in metallic systems. However, the size of the Kondo scattering is at least an order of magnitude larger than in metallic systems. Further, from the extrapolation of the Kondo temperature we are able to predict that Ta is a better candidate for observation of ferromagnetism versus Nb.

The observation of two dimensional electron gas (2DEG), superconductivity and magnetism at the in... more The observation of two dimensional electron gas (2DEG), superconductivity and magnetism at the interfaces of LaAlO 3 /SrTiO 3 has further amplified the potential of complex oxides for novel electronics. These multifunctional properties are strongly believed to originate from the polarization discontinuity at the interface between the two oxides along (001) direction. In this scenario, the crystal orientation plays an important role and no conductivity would be expected for e.g., the interface between LaAlO 3 and (110)-oriented SrTiO 3 , which should not have a polarization discontinuity. In this talk, we will show the observation of conductivity at the LaAlO 3 /SrTiO 3 interface prepared on (110)-oriented SrTiO 3. The strong evidence for 2DEG at the interface of LaAlO 3 /SrTiO 3 (110) is the observed thickness dependence of insulator-metal transition at 3-4 u.c of LaAlO 3. Directional dependent electrical transport is observed in resistance versus temperature measurements. We propose some models for explaining the observed phenomena.

Physical Review Letters, 2011

We report optical, electrical and magneto transport properties of a high quality oxygen deficient... more We report optical, electrical and magneto transport properties of a high quality oxygen deficient SrTiO3 (STO) thin film fabricated by pulsed laser deposition technique. The oxygen vacancy distribution in the thin film is expected to be uniform. By comparing its electrical properties to those of oxygen deficient bulk STO, it was found that the oxygen vacancies in bulk STO is far from uniform over the whole material. The metal-insulator transition (MIT) observed in the oxygen deficient STO film was found to be induced by the carrier freeze-out effect. The low temperature frozen state can be re-excited by Joule heating, electric and intriguingly magnetic field.

Journal of Applied Physics, 2009

In this paper, we report on the results of temperature dependent impedance measurements on chemic... more In this paper, we report on the results of temperature dependent impedance measurements on chemical solution deposited BiFeO3 thin films on Pt/Si substrates. X-ray diffraction analysis showed the presence of predominately single phase BiFeO3. The measurements were made in the frequency range of 100–107 Hz and between 27 and 250 °C. Plots between real and imaginary parts of impedance (Z′ and Z″) and electrical modulus (M′ and M″) in the above frequency and temperature domain suggest the presence of two relaxation regimes which are attributed to bulk and grain boundary responses. Below 150 °C, both conductivity and real dielectric constant show a steplike behavior. The frequency independent regions in 10–100 kHz indicate relaxation of the bulk conduction, while at lower frequency there is a strong frequency dependence associated with the dispersion toward relaxation of the grain boundary. In contrast, at and above 150 °C, frequency independent behavior of dc conduction becomes dominan...

Indian Journal of …, 2007

Indian Journal of Pure & Applied Physics Vol. 45, April 2007, pp. 395-399 ... Nano-structured ZnO... more Indian Journal of Pure & Applied Physics Vol. 45, April 2007, pp. 395-399 ... Nano-structured ZnO films by sol-gel process ... Harish Bahadur, AK Srivastava, Divi Haranath, Harish Chander, A Basu, SB Samanta, KN Sood, Ram Kishore, RK Sharma, Rashmi, ...

Journal of Applied Physics, 2009

We measured the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a [001] o... more We measured the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a [001] oriented epitaxial thin film of La0.7Ca0.3MnO3 (LCMO) as a function of magnetic field, temperature, and current direction relative to the crystal axes. We find that both AMR and PHE in LCMO depend strongly on the current orientation relative to the crystal axes, and we demonstrate the applicability of AMR and PHE equations based on a fourth order magnetoresistance tensor consistent with the film symmetry.

SN Applied Sciences

The Bi-Al doped M-type hexaferrite (BaFe 11.8 Bi 0.1 Al 0.1 O 19) was prepared by the use of sol ... more The Bi-Al doped M-type hexaferrite (BaFe 11.8 Bi 0.1 Al 0.1 O 19) was prepared by the use of sol gel auto combustion process. The prepared sample was sintered at 1000 °C for 5 h. Polyaniline was synthesized by oxidative polymerization. Mechanical blending was used to synthesize BaFe 11.8 Bi 0.1 Al 0.1 O 19-PANI composite. X-ray diffraction (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Field Emission Scanning Electron Microscope, Energy Dispersive X-ray spectroscopy and UV-vis-NIR spectroscopy were used for structural and optical analysis. XRD spectra show pure single phase of M-type hexagonal ferrites. The presence of bands in FTIR spectra in the range of 400-600 cm −1 and 800-1600 cm −1 indicate possible formation of hexaferrite and PANI. The band gaps were found nearly 2.24, 2.36 and 2.21 eV for HP1, HP2 and HP3 respectively.

Journal of Physics: Conference Series

Scientific reports, Jan 7, 2015

Metamaterials open up various exotic means to control electromagnetic waves and among them polari... more Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tun...

Advanced Electronic Materials, 2015

Manipulating spin-orbit coupling (SOC) is important for devices such as spinorbit torque based me... more Manipulating spin-orbit coupling (SOC) is important for devices such as spinorbit torque based memory and its understanding is neccessary to answer several fundamental open questions in triplet state superconductivity, topological insulators and Majorana fermions. Here we report spin splitting of 25 meV at the LaAlO 3 /SrTiO 3 (110) interface for in-plane spins at a current density of 1.4x10 4 A/cm 2 , which is large compared to that found in semiconductor heterostructures or the LaAlO 3 /SrTiO 3 (100) interface, and in addition it is anisotropic. The anisotropy arises from the difference in electron effective mass along the [001] and [1-10] directions. Our study predicts a spin splitting energy > 1000 meV at a current density of 10 7 A/cm 2 , which is enormous compared to metallic systems and will be an ideal spin polarized source. In addition to the in-plane effect, there is an unexpected gate-tunable out-of-plane SOC at the LaAlO 3 /SrTiO 3 (110) interface when the spins lie out-of-plane due to broken symmetry in the plane of the interface. We demonstrate that this can be manipulated by varying the LaAlO 3 thickness showing that this interface can be engineered for spin-orbit torque devices.

J. Mater. Chem. C, 2015

Substitution of Ti with Nb or Ta in epitaxial thin films of anatase TiO2 induces large and small ... more Substitution of Ti with Nb or Ta in epitaxial thin films of anatase TiO2 induces large and small polarons.

In this letter, we report anisotropic gate tunable Rashba spin-orbit interaction (SOI) at LaAlO3/... more In this letter, we report anisotropic gate tunable Rashba spin-orbit interaction (SOI) at LaAlO3/SrTiO3(110) interface with a large spin splitting energy of 25 meV with two different LaAlO3 layer thicknesses which enable us to study SOI with strain, z-confinement and band filling effects. The anisotropy in SOI is understood to arise from the difference in electron effective mass along [001] and [1-10]. We see a clear evidence of gate tunable out-of-plane SOI in addition to the in-plane SOI due to a broken symmetry in the plane of the interface and its relative contribution is determined by z-confinement.

I particularly want to thank Dr. Helene Rotella who joined NanoCore when I was in my last year of... more I particularly want to thank Dr. Helene Rotella who joined NanoCore when I was in my last year of Ph.D. Her experimental expertise and analytical skills have improved my understanding on my research work. I cannot be thankful enough to her for encouraging me and giving me moral support during the most difficult times while writing this thesis. Finally and most importantly, I want to express my love and gratitude to family members. My parents, brother Gaurav, sisters Garima and Pooja-you are the source of my sustenance. I could not have asked for anything more from you. It is all because of you. Thank you for being so patient and supportive especially during the time of my

Scientific reports, Nov 15, 2016

Here, we report the presence of defect-related states with magnetic degrees of freedom in crystal... more Here, we report the presence of defect-related states with magnetic degrees of freedom in crystals of LaAlO3 and several other rare-earth based perovskite oxides using inelastic light scattering (Raman spectroscopy) at low temperatures in applied magnetic fields of up to 9 T. Some of these states are at about 140 meV above the valence band maximum while others are mid-gap states at about 2.3 eV. No magnetic impurity could be detected in LaAlO3 by Proton-Induced X-ray Emission Spectroscopy. We, therefore, attribute the angular momentum-like states in LaAlO3 to cationic/anionic vacancies or anti-site defects. Comparison with the other rare earth perovskites leads to the empirical rule that the magnetic-field-sensitive transitions require planes of heavy elements (e.g. lanthanum) and oxygen without any other light cations in the same plane. These magnetic degrees of freedom in rare earth perovskites with useful dielectric properties may be tunable by appropriate defect engineering for ...

Understanding and manipulating the spin-orbit coupling (SOC) in electronic systems is important f... more Understanding and manipulating the spin-orbit coupling (SOC) in electronic systems is important for spintronics devices and also for the fundamental phenomena such as triplet state superconductivity, topological insulators and Majorana fermions which are forefront topics in condensed matter physics today. In this experimental paper, we report gate tunable anisotropic Rashba spin-orbit coupling (SOC) at LaAlO3/SrTiO3(110) interface with a large spin splitting energy of 25 meV as compared to semiconductor heterostructures. The anisotropy in SOC is understood to arise from the difference in electron effective mass along [001] and [1-10]. Samples of two different LaAlO3 thicknesses were chosen to study the effect of strain, z-confinement, band filling and crystal orientation on SOC. We see a clear evidence of gate tunable out-of-plane SOC in addition to the usual in-plane SOC due to a broken symmetry in the plane of the interface and its relative contribution is determined by the extent of z-confinement. Our study clearly shows that the orbital occupancy and the strength of SOC are not explicitly related.

Physical Review B, 2015

Vanadium dioxide (VO 2) undergoes an unusual insulator-metal transition (IMT), and after decades ... more Vanadium dioxide (VO 2) undergoes an unusual insulator-metal transition (IMT), and after decades of study, the origin of the IMT remains hotly debated. Here, by analyzing spectral-weight transfers (SWTs) of x-ray absorption spectroscopy at the V L 3,2 and O K edges on specially designed VO 2 films, we observe d || (d x 2 −y 2) band splitting at the V L 3,2 edges across the IMT, accompanied by anomalous SWTs as high as ∼12 eV at the O K edge, indicating strong electronic correlations. Surprisingly, a few oxygen vacancies induce dramatic SWTs at the O K edge, but the sample remains conducting. Supported by theoretical calculations, we find that in the metallic state, direct V(3d)-V(3d) and O(2p)-V(3d) hybridized orbital correlations are screened by O(2p)-V(3d π) hybridized orbitals, while in the insulating state they are strongly correlated due to changes in the oxygen orbital occupancy. Our result shows the importance of screenings and electronic correlations for IMTs in VO 2 .

117576-We show that Ti 0.94 M 0.06 O 2 (M = Nb, Ta) thin films are Kondo systems by angle depende... more 117576-We show that Ti 0.94 M 0.06 O 2 (M = Nb, Ta) thin films are Kondo systems by angle dependent magneto-resistance measurement. Surprisingly, the data fitted by both Goldhaber-Gordon and Hamann formula yield comparable carrier dependent Kondo temperatures (10-60 K). The Kondo temperature dependence on carrier density was different for Ta and Nb incorporated in TiO 2 but this result could be understood on the basis of the formation of compensating defects (Ti vacancies) which also act as localized magnetic scattering centers. Using the unitarity-limit resistivity and Kondo temperature estimated from these fits the normalized resistivity versus temperature for all these films collapse into a universal curve consistent with data observed in metallic systems. However, the size of the Kondo scattering is at least an order of magnitude larger than in metallic systems. Further, from the extrapolation of the Kondo temperature we are able to predict that Ta is a better candidate for observation of ferromagnetism versus Nb.

The observation of two dimensional electron gas (2DEG), superconductivity and magnetism at the in... more The observation of two dimensional electron gas (2DEG), superconductivity and magnetism at the interfaces of LaAlO 3 /SrTiO 3 has further amplified the potential of complex oxides for novel electronics. These multifunctional properties are strongly believed to originate from the polarization discontinuity at the interface between the two oxides along (001) direction. In this scenario, the crystal orientation plays an important role and no conductivity would be expected for e.g., the interface between LaAlO 3 and (110)-oriented SrTiO 3 , which should not have a polarization discontinuity. In this talk, we will show the observation of conductivity at the LaAlO 3 /SrTiO 3 interface prepared on (110)-oriented SrTiO 3. The strong evidence for 2DEG at the interface of LaAlO 3 /SrTiO 3 (110) is the observed thickness dependence of insulator-metal transition at 3-4 u.c of LaAlO 3. Directional dependent electrical transport is observed in resistance versus temperature measurements. We propose some models for explaining the observed phenomena.

Physical Review Letters, 2011

We report optical, electrical and magneto transport properties of a high quality oxygen deficient... more We report optical, electrical and magneto transport properties of a high quality oxygen deficient SrTiO3 (STO) thin film fabricated by pulsed laser deposition technique. The oxygen vacancy distribution in the thin film is expected to be uniform. By comparing its electrical properties to those of oxygen deficient bulk STO, it was found that the oxygen vacancies in bulk STO is far from uniform over the whole material. The metal-insulator transition (MIT) observed in the oxygen deficient STO film was found to be induced by the carrier freeze-out effect. The low temperature frozen state can be re-excited by Joule heating, electric and intriguingly magnetic field.

Journal of Applied Physics, 2009

In this paper, we report on the results of temperature dependent impedance measurements on chemic... more In this paper, we report on the results of temperature dependent impedance measurements on chemical solution deposited BiFeO3 thin films on Pt/Si substrates. X-ray diffraction analysis showed the presence of predominately single phase BiFeO3. The measurements were made in the frequency range of 100–107 Hz and between 27 and 250 °C. Plots between real and imaginary parts of impedance (Z′ and Z″) and electrical modulus (M′ and M″) in the above frequency and temperature domain suggest the presence of two relaxation regimes which are attributed to bulk and grain boundary responses. Below 150 °C, both conductivity and real dielectric constant show a steplike behavior. The frequency independent regions in 10–100 kHz indicate relaxation of the bulk conduction, while at lower frequency there is a strong frequency dependence associated with the dispersion toward relaxation of the grain boundary. In contrast, at and above 150 °C, frequency independent behavior of dc conduction becomes dominan...

Indian Journal of …, 2007

Indian Journal of Pure & Applied Physics Vol. 45, April 2007, pp. 395-399 ... Nano-structured ZnO... more Indian Journal of Pure & Applied Physics Vol. 45, April 2007, pp. 395-399 ... Nano-structured ZnO films by sol-gel process ... Harish Bahadur, AK Srivastava, Divi Haranath, Harish Chander, A Basu, SB Samanta, KN Sood, Ram Kishore, RK Sharma, Rashmi, ...

Journal of Applied Physics, 2009

We measured the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a [001] o... more We measured the anisotropic magnetoresistance (AMR) and the planar Hall effect (PHE) in a [001] oriented epitaxial thin film of La0.7Ca0.3MnO3 (LCMO) as a function of magnetic field, temperature, and current direction relative to the crystal axes. We find that both AMR and PHE in LCMO depend strongly on the current orientation relative to the crystal axes, and we demonstrate the applicability of AMR and PHE equations based on a fourth order magnetoresistance tensor consistent with the film symmetry.

SN Applied Sciences

The Bi-Al doped M-type hexaferrite (BaFe 11.8 Bi 0.1 Al 0.1 O 19) was prepared by the use of sol ... more The Bi-Al doped M-type hexaferrite (BaFe 11.8 Bi 0.1 Al 0.1 O 19) was prepared by the use of sol gel auto combustion process. The prepared sample was sintered at 1000 °C for 5 h. Polyaniline was synthesized by oxidative polymerization. Mechanical blending was used to synthesize BaFe 11.8 Bi 0.1 Al 0.1 O 19-PANI composite. X-ray diffraction (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Field Emission Scanning Electron Microscope, Energy Dispersive X-ray spectroscopy and UV-vis-NIR spectroscopy were used for structural and optical analysis. XRD spectra show pure single phase of M-type hexagonal ferrites. The presence of bands in FTIR spectra in the range of 400-600 cm −1 and 800-1600 cm −1 indicate possible formation of hexaferrite and PANI. The band gaps were found nearly 2.24, 2.36 and 2.21 eV for HP1, HP2 and HP3 respectively.

Journal of Physics: Conference Series

Scientific reports, Jan 7, 2015

Metamaterials open up various exotic means to control electromagnetic waves and among them polari... more Metamaterials open up various exotic means to control electromagnetic waves and among them polarization manipulations with metamaterials have attracted intense attention. As of today, static responses of resonators in metamaterials lead to a narrow-band and single-function operation. Extension of the working frequency relies on multilayer metamaterials or different unit cells, which hinder the development of ultra-compact optical systems. In this work, we demonstrate a switchable ultrathin terahertz quarter-wave plate by hybridizing a phase change material, vanadium dioxide (VO2), with a metasurface. Before the phase transition, VO2 behaves as a semiconductor and the metasurface operates as a quarter-wave plate at 0.468 THz. After the transition to metal phase, the quarter-wave plate operates at 0.502 THz. At the corresponding operating frequencies, the metasurface converts a linearly polarized light into a circularly polarized light. This work reveals the feasibility to realize tun...

Advanced Electronic Materials, 2015

Manipulating spin-orbit coupling (SOC) is important for devices such as spinorbit torque based me... more Manipulating spin-orbit coupling (SOC) is important for devices such as spinorbit torque based memory and its understanding is neccessary to answer several fundamental open questions in triplet state superconductivity, topological insulators and Majorana fermions. Here we report spin splitting of 25 meV at the LaAlO 3 /SrTiO 3 (110) interface for in-plane spins at a current density of 1.4x10 4 A/cm 2 , which is large compared to that found in semiconductor heterostructures or the LaAlO 3 /SrTiO 3 (100) interface, and in addition it is anisotropic. The anisotropy arises from the difference in electron effective mass along the [001] and [1-10] directions. Our study predicts a spin splitting energy > 1000 meV at a current density of 10 7 A/cm 2 , which is enormous compared to metallic systems and will be an ideal spin polarized source. In addition to the in-plane effect, there is an unexpected gate-tunable out-of-plane SOC at the LaAlO 3 /SrTiO 3 (110) interface when the spins lie out-of-plane due to broken symmetry in the plane of the interface. We demonstrate that this can be manipulated by varying the LaAlO 3 thickness showing that this interface can be engineered for spin-orbit torque devices.

J. Mater. Chem. C, 2015

Substitution of Ti with Nb or Ta in epitaxial thin films of anatase TiO2 induces large and small ... more Substitution of Ti with Nb or Ta in epitaxial thin films of anatase TiO2 induces large and small polarons.

In this letter, we report anisotropic gate tunable Rashba spin-orbit interaction (SOI) at LaAlO3/... more In this letter, we report anisotropic gate tunable Rashba spin-orbit interaction (SOI) at LaAlO3/SrTiO3(110) interface with a large spin splitting energy of 25 meV with two different LaAlO3 layer thicknesses which enable us to study SOI with strain, z-confinement and band filling effects. The anisotropy in SOI is understood to arise from the difference in electron effective mass along [001] and [1-10]. We see a clear evidence of gate tunable out-of-plane SOI in addition to the in-plane SOI due to a broken symmetry in the plane of the interface and its relative contribution is determined by z-confinement.