Showing papers on "Magnetocapacitance published in 2013"
TL;DR: In this paper, BaTiO3-ferrite multiphase composites were prepared starting from di-phase mixtures of α-Fe2O3 and β-FeO3 powders.
Abstract: BaTiO3–ferrite multiphase composites were prepared starting from di-phase mixtures of α-Fe2O3 and BaTiO3 powders. During the sintering step, the formation of small amounts of secondary phases with multifunctional character as BaFe12O19 or Ba12Ti28Fe15O84 was promoted. The resulting multiphase ceramic compounds show interesting dielectric, magnetic and small magnetocapacitance effect at low temperature. The coexistence of different magnetic phases with contrasting coercivities (hard/soft) was detected by the presence of ‘wasp-waisted’ M(H) hysteresis loops and first-order reversal curve analysis. The present approach demonstrates that active materials can be realised by controlling in situ reactions at the interfaces in ferroelectric–magnetic oxide composites.
26 citations
TL;DR: In this paper, the magnetoelectric response in composites of barium titanate (BTO) and cobalt ferrite (CFO) has been determined by measuring the magnetic susceptibility coefficient.
24 citations
TL;DR: In this paper, multiferroic composite nanoparticles of CoFe2O4 and perovskite Bi 0.85La 0.15FeO3 were prepared by a two-step wet chemical procedure, combining co-precipitation and sol-gel techniques.
23 citations
TL;DR: The neutron diffraction experiment under the magnetic field proves the origin of the dielectric property related to the motion of the nanosized ferromagnetic domain boundary and implies that the modification of the microscopic domain structure is responsible for the magnetoelectric effect in LuFe(2)O(4).
Abstract: The magnetocapacitance effect was investigated using impedance spectroscopy on single crystals of LuFe(2)O(4). The intrinsic impedance response could be separated from the interfacial response and showed a clear hysteresis loop below T(Ferri)∼240 K under the magnetic field. The neutron diffraction experiment under the magnetic field proves the origin of the dielectric property related to the motion of the nanosized ferromagnetic domain boundary. These results imply that the modification of the microscopic domain structure is responsible for the magnetoelectric effect in LuFe(2)O(4).
22 citations
TL;DR: Determining the density of states, it is found that the electron-hole symmetry is broken when the Zeeman and hybridization energies are varied relative to each other, which leads to a change in the character of the magnetocapacitance at the charge neutrality point.
Abstract: We present a theoretical study of the quantum magnetocapacitance of an ultrathin topological insulator film in an external magnetic field. The study is undertaken to investigate the interplay of the Zeeman interaction with the hybridization between the upper and lower surfaces of the thin film. Determining the density of states, we find that the electron-hole symmetry is broken when the Zeeman and hybridization energies are varied relative to each other. This leads to a change in the character of the magnetocapacitance at the charge neutrality point. We further show that in the presence of both Zeeman interaction and hybridization the magnetocapacitance exhibits beating at low and splitting of the Shubnikov de Haas oscillations at high perpendicular magnetic field. In addition, we address the crossover from perpendicular to parallel magnetic field and find consistency with recent experimental data.
22 citations
TL;DR: In this paper, the dielectric, magnetoelectric and magnetodielectric properties of Co1.2Fe1.8−xMnxO4 and Pb0.2Ba0.8TiO3 composites are reported.
20 citations
TL;DR: In this article, the authors reported the synthesis of magnetoelectric composites via ceramic and hydroxide co-precipitation routes via Co 1.2−x Mn x Fe 1.8 O 4 (CMFO) via a sintering aid, where Bi 2 O 3 at three weight percent is observed to cause agglomeration of SBN and CMFO particles and improve the magneto-mechanical coupling.
19 citations
TL;DR: In this paper, the magnetic hysteresis loop exhibits typical signature of a soft ferromagnetic character at room temperature in contrast to that observed in antiferromagnetic bulk counterpart.
Abstract: We report significantly large magnetocapacitance (∼32%) close to room temperature in Cr2O3 film fabricated using pulsed laser deposition technique. Magnetic hysteresis loop exhibits typical signature of a soft ferromagnetic character at room temperature in contrast to that observed in antiferromagnetic bulk counterpart. The value of saturation magnetization (MS) is significantly large with MS≈1.0μB at room temperature. A significant strain ascribed to the lattice mismatch is suggested for the occurrence of ferromagnetism and is correlated to the significant magnetocapacitance close to room temperature.
19 citations
TL;DR: In this article, a sample of the layered perovskite phase was successfully obtained and the measurement of x-ray photoelectron spectroscopy indicated the coexistence of Fe3+ and Fe2+ ions.
Abstract: (Bi3.15Nd0.85)(Ti2Fe0.5Co0.5)O12−δ ceramics were prepared by the conventional solid-state reaction method. The sample of the layered perovskite phase was successfully obtained. The measurement of x-ray photoelectron spectroscopy indicated the coexistence of Fe3+ and Fe2+ ions. The multiferroic behaviour of the sample at room temperature (RT) was demonstrated by the ferroelectric (2Pr = 8 µC cm−2, 2Ec = 64 kV cm−1 at applied electric field 86 kV cm−1) and ferromagnetic (2Mr = 32 m emu g−1, 2Hc = 872 Oe at applied magnetic field 1.1 T) hysteresis loops. Remarkably, a clearly identified positive magnetocapacitance effect was observed with a large magnetocapacitance value of ~14.2% at 30 kHz. Comparison of the impedance Cole–Cole plots measured with and without magnetic field revealed that the occurrence of magnetocapacitance effect is accompanied by an increase in the conductivity under magnetic field, which is explained by the enhancement of electron jumping in Fe2+–O–Fe3+ chains by magnetic field. The present results suggest a new candidate for a RT multiferroic material with large magnetocapacitance effect.
15 citations
TL;DR: In this article, the magnetoelectric, dielectric and magnetic properties of x Co 0.7 Zn 0.3 Fe 2 O 4 −(1− ǫ x )Bi 0.9 La 0.4 were reported.
15 citations
TL;DR: In this paper, single-phase co-doped (La 3+, Lu 3+ ) in Bi 0.95− x La 0.05 Lu x FeO 3 (x ǫ= 0.03, 0.04, 0.05 and 0.07) were prepared by solid state reaction of oxides, followed by rapid quenching of samples.
TL;DR: Through investigating the spin-dependent charging energy of nanoscale systems, a new concept of intrinsic molecular magnetocapacitance (MC) is introduced, which can be as high as 12%.
Abstract: Capacitance of a nanoscale system is usually thought of having two contributions, a classical electrostatic contribution and a quantum contribution dependent on the density of states and/or molecular orbitals close to the Fermi energy. In this letter we demonstrate that in molecular nano-magnets and other magnetic nanoscale systems, the quantum part of the capacitance becomes spin-dependent, and is tunable by an external magnetic field. This molecular magnetocapacitance can be realized using single molecule nano-magnets and/or other nano-structures that have antiferromagnetic ground states. As a proof of principle, first-principles calculation of the nano-magnet [Mn3O(sao)3(O2CMe)(H2O)(py)3] shows that the charging energy of the high-spin state is 260 meV lower than that of the low-spin state, yielding a 6% difference in capacitance. A magnetic field of ~40T can switch the spin state, thus changing the molecular capacitance. A smaller switching field may be achieved using nanostructures with a larger moment. Molecular magnetocapacitance may lead to revolutionary device designs, e.g., by exploiting the Coulomb blockade magnetoresistance whereby a small change in capacitance can lead to a huge change in resistance.
TL;DR: The most striking result is that the bulk material made of the Bi4.2K0.8Fe2O9+δ nanobelts is of multiferroicity near room temperature accompanied with a structure anomaly.
Abstract: Magnetoelectric multiferroics are materials that have coupled magnetic and electric dipole orders, which can bring novel physical phenomena and offer possibilities for new device functions. In this report, single-crystalline Bi4.2K0.8Fe2O9+δ nanobelts which are isostructural with the high-temperature superconductor Bi2Sr2CaCu2O8+δ are successfully grown by a hydrothermal method. The regular stacking of the rock salt slabs and the BiFeO3-like perovskite blocks along the c axis of the crystal makes the Bi4.2K0.8Fe2O9+δ nanobelts have a natural magnetoelectric–dielectric superlattice structure. The most striking result is that the bulk material made of the Bi4.2K0.8Fe2O9+δ nanobelts is of multiferroicity near room temperature accompanied with a structure anomaly. When an external magnetic field is applied, the electric polarization is greatly suppressed, and correspondingly, a large negative magnetocapacitance coefficient is observed around 270 K possibly due to the magnetoelectric coupling effect. Our result provides contributions to the development of single phase multiferroics.
TL;DR: In this article, the structural and electrical properties of Mn3GaN epitaxial thin films with an inverse perovskite structure have been investigated and it has been found that these thin films exhibit a large magnetocapacitance effect of more than 2000% in an applied magnetic filed of 1.5 T. The maximum resistivity could be attributed to the magnetic transition from antiferromagneticnetism to paramagnetism.
Abstract: Thin films and heterostructures of Mn3GaN with an inverse perovskite structure were grown epitaxially on SrTiO3 (001) and (La0.18Sr0.82)(Al0.59Ta0.41)O3 (001) (LSAT) substrates by ion beam sputtering, and their structural and electrical properties have been investigated. Mn3GaN epitaxial thin films showed metallic behavior of temperature-dependent resistivity with a small maximum at 290–340 K. The maximum resistivity could be attributed to the magnetic transition from antiferromagnetism to paramagnetism. It has been found that epitaxial heterostructures formed by ferroelectric Ba0.7Sr0.3TiO3 and Mn3GaN layers exhibit a large magnetocapacitance effect of more than 2000% in an applied magnetic filed of 1.5 T.
TL;DR: In this article, Terfenol-D/Pt/PZT stack was sputtered on Pt/TiO2/SiO 2/SiSi/Si substrate.
Abstract: Tb0.3Dy0.7Fe2/Pt/PbZr0.56Ti0.44O3 (Terfenol-D/Pt/PZT) thin films were sputtered on Pt/TiO2/SiO2/Si substrate. PZT and Terfenol-D layers were chosen for their large piezoelectric and magnetostrictive coefficients, respectively. 4%–5% magnetocapacitance has been measured on a Terfenol-D/Pt/PZT stack at room temperature. A magnetoelectric (ME) voltage coefficient of 150 mV/cm Oe was obtained at low dc magnetic field out of mechanical resonance. This work demonstrates the possibility to achieve ME effect in integrated devices involving Terfenol-D and PZT thin films providing that the diffusion, which may occur between both active layers is reduced using an intermediate layer.
TL;DR: It is concluded that the doped spin radicals can have the spin interaction with intermolecular excited states and consequently affect the internal spin-exchange interaction within interm Molecule excited states in the development of MFC.
Abstract: This article reports the magnetocapacitance effect (MFC) based on both pristine polymer MEH-PPV and its composite system doped with spin radicals (6R-BDTSCSB). We observed that a photoexcitation leads to a significant positive MFC in the pristine MEH-PPV. Moreover, we found that a low doping of spin radicals in polymer MEH-PPV causes a significant change on the MFC signal: an amplitude increase and a line-shape narrowing under light illumination at room temperature. However, no MFC signal was observed under dark conditions in either the pristine MEH-PPV or the radical-doped MEH-PPV. Furthermore, the magnitude increase and line-shape narrowing caused by the doped spin radicals are very similar to the phenomena induced by increasing the photoexcitation intensity. Our studies suggest that the MFC is essentially originated from the intermolecular excited states, namely, intermolecular electron–hole pairs, generated by a photoexcitation in the MEH-PPV. More importantly, by comparing the effects of spin radical...
TL;DR: In this paper, the emergence of Fe2+ was shown to be very important for the ferroelectric, magnetoelectric and magnetocapacitance properties of Ho3Fe5O12 ceramics.
Abstract: Iron garnet Ho3Fe5O12 ceramics, in which Ho3+ is a rare earth ion with strong magnetic moment, were prepared and carefully studied. The emergence of Fe2+ was shown to be very important for the ferroelectric, magnetoelectric (ME) and magnetocapacitance (MC) properties of Ho3Fe5O12 ceramics. Room temperature P-E hysteresis loops that were never reported before for iron garnets were explained by local dipoles related with Fe2+. The ME coupling indicated by the magnetic field-induced variation of remanent polarization was further confirmed by oxygen treatment. The MC effect was observed in a broad temperature range (2–300 K) and it is also connected to the presence of Fe2+.
TL;DR: In this article, the electronic, thermoelectric, and magneto-dielectric properties of Ca1−xNaxCr2O4 series with a calcium ferrite-type structure prepared by high-pressure-high-temperature synthesis were reported.
Abstract: We report on electronic, thermoelectric, and magneto-dielectric properties of Ca1−xNaxCr2O4 series with a calcium ferrite-type structure prepared by high-pressure-high-temperature synthesis. Dielectric spectroscopy down to 2 K confirms that both CaCr2O4 and NaCr2O4 end members have an insulating ground state notwithstanding the fact that the latter compound has a mixed valence Cr3+/Cr4+ structure. A crossover from positive to negative charge carriers occurs in NaCr2O4 at T≈230 K. Partial substitution of Ca for Na brings about a change from n to p type carriers at ca. x=0.75. A strong suppression of thermal conductivity below TN=21 K was found in CaCr2O4 indicating a scattering of acoustic phonons from a long wave-length cycloidal magnetic excitations. A pronounced dielectric anomaly at Neel temperature adds CaCr2O4 to the multiferroic family of compounds. Lattice contribution to dielectric properties of NaCr2O4 at TN=125 K is screened by high electric conductivity. An onset of the magnetocapacitance above...
TL;DR: In this paper, the dielectric, magnetodielectric and magnetoelectric properties of Mn-substituted Co1.8O4 (CMFO) and Pb0.2Ba0.8TiO3 (PBT) composites are reported.
Abstract: The present paper reports the dielectric, magnetodielectric, and magnetoelectric properties of Mn-substituted Co1.2−x
Mn
x
Fe1.8O4 (CMFO) and Pb0.2Ba0.8TiO3 (PBT) magnetoelectric (ME) composites. The Co1.2−x
Mn
x
Fe1.8O4 is initially studied for variation of electrical resistivity ρ, saturation magnetization M
s, permeability μ, coercive field H
c, and coefficient of magnetostriction λ to determine compositions suitable to form the ME composite. Here, x = 0.4 and 0.1 are observed to possess optimum values of ρ, M
s, μ, H
c, and λ; therefore, the composites are formed using Co0.8Mn0.4Fe1.8O4 (CMFO 0.4) as well as Co1.1Mn0.1Fe1.8O4 (CMFO 0.1). The composites were synthesized and investigated for their structural, dielectric, magnetoelectric, and magnetodielectric properties. The dielectric constant of the composites is observed to exhibit a contribution due to interfacial polarization as well as a contribution due to the PBT phase. The variation of the linear magnetoelectric coefficient, α, quadratic magnetoelectric coefficient, β, and magnetocapacitance, M
c, for various compositions are reported in this paper. The paper also reports the effect of sintering temperature and variation of frequency on the magnitude of α and M
c. The samples with y = 0.5 are observed to show a sufficiently large and useful magnitude of magnetoelectric coefficients and M
c value.
TL;DR: In this article, the magnetization and transport properties of iron-phthalocyanine molecular conductors were investigated under pulsed high magnetic fields up to 55 T, where conductivity is enhanced.
Abstract: The magnetization and transport properties of iron-phthalocyanine molecular conductors are investigated under pulsed high magnetic fields up to 55 T. The metamagnetic transition is observed at approximately 14 T, where conductivity is enhanced. Below this transition, the tan δ (=e′′/e′) in the dielectric constants shows a monotonic decrease as the magnetic field strength increases, indicating that the magnetic field stabilizes the charge order. On the verge of this transition, the dielectric constants show a hysteresis below the weak-ferromagnetic transition temperature (6 K), suggesting that the π-electron charge order contributes to the weak ferromagnetism.
TL;DR: In this article, the effect of magnetic field on AC conductivity was analyzed in terms of a possible equivalent circuit model and the present analysis showed that the method of impedance spectra could be used to separate out the possible contributions to the magnetodielectric effect.
Abstract: The paper discuses synthesis of La0.67Sr0.33MnO3 and BaZr0.15Ti0.85O3 thin film heterostructures using modified Pechini method (citrate gel) and spin coating technique. The XRD spectra are determined for confirmation of the crystal structure and phase formation of thin film composites. The paper presents variation of real and imaginary parts of dielectric constant e′, e″ and tan δ as function of frequency between 100 Hz and 1 MHz and applied magnetic field up to 0.6 T. The paper, also discuses the effect of magnetic field on AC conductivity. The observed variation of magnetocapacitance and impedance spectra are analyzed in terms of a possible equivalent circuit model. The present analysis shows that the method of impedance spectra could be used to separate out the possible contributions to the magnetodielectric effect.
TL;DR: In this article, the properties of 0.94BNT-0.06BT/xNiO lead-free nanocomposites were investigated and the NiO additive influenced dielectric properties as well as the phase transition behavior of the samples.
Abstract: The properties of 0.94BNT-0.06BT/xNiO lead-free nanocomposites were investigated. The NiO additive influenced dielectric properties as well as the phase transition behavior of the samples. Dielectric properties under applied magnetic fields were also measured. After addition of the additive, the loss tangent could be controlled by an applied magnetic field. Furthermore, the P-E hysteresis loop changed from a normal hysteresis loop for the unmodified sample to a constricted loop for the x = 0.5 and 1.0 vol. % samples, and then became a lossy capacitor hysteresis loop for the x = 2.0 vol. % sample. These results suggest that NiO nanoparticles have a strong influence on the properties of the composites.
TL;DR: The origin of colossal magnetoresistance and colossal magnetocapacitance in a CdCr2S4 system was investigated in this paper, where the existence of magnetic polarons in the paramagnetic matrix formed an intrinsic Maxwell-Wagner system.
Abstract: The origin of colossal magnetoresistance and colossal magnetocapacitance in a CdCr2S4 system was investigated. Thermoelectric-power and electronic spin resonance spectra reveal that the magnetic polaron is responsible for the colossal magnetoresistance in the n-type sample. The existence of magnetic polarons in the paramagnetic insulting matrix forms an intrinsic Maxwell-Wagner system, leading to the appearance of colossal magnetocapacitance. Being consistent with the evolution of magnetic polarons upon cooling, the Maxwell-Wagner system is valid around insulator-metal transition, where the resistance derived from impedance spectroscopy matches perfectly with DC resistance.
TL;DR: In this article, the magnetic and dielectric properties of the quasi-two-dimensional triangular lattice system CuCrS2 and its B-site-diluted analogs CuAl1−xCrxS2 (x = 0.01 and x =0.02) are investigated.
Abstract: In this paper, magnetic and dielectric properties of the quasi-two-dimensional triangular-lattice system CuCrS2 and its B-site-diluted analogs CuAl1−xCrxS2 (x = 0.01 and x = 0.02) are investigated. Antiferromagnetic phase transition is observed at about 38.5 K by magnetization measurement without shift induced by a small amount of doping Al. Magnetodielectric effect is found near TN in each of the three compounds. The dielectric constant decreases and the magnetocapacitance increases with the increase of substitution of nonmagnetic Al3+ ions for the magnetic Cr3+ ions. The negative magnetocapacitive effect reaches ~ 13% for CuAl0.02Cr0.98S2.
TL;DR: In this paper, the authors observed a sizable positive magnetocapacitance (∼5% to 90%) in perovskite Pr0.55Ca0.45MnO3 and bilayer Pr(Sr0.1Ca 0.9)2Mn2O7 systems under 5'T magnetic field across 20 -100'K below the magnetic transition point TN.
Abstract: We have observed a sizable positive magnetocapacitance (∼5%–90%) in perovskite Pr0.55Ca0.45MnO3 and bilayer Pr(Sr0.1Ca0.9)2Mn2O7 system under 5 T magnetic field across 20–100 K below the magnetic transition point TN. The magnetodielectric effect, on the other hand, exhibits a crossover: (a) from positive to negative for the perovskite system and (b) from negative to positive for the bilayer system over the same temperature range. The bilayer Pr(Sr0.1Ca0.9)2Mn2O7 system exhibits a sizable anisotropy as well. We have also noticed the influence of magnetic field on the dielectric relaxation characteristics of these systems. These systems belong to a class of improper ferroelectrics and are expected to exhibit charge/orbital order driven ferroelectric polarization below the transition point TCO. Large magnetocapacitance in these systems shows a typical multiferroic behavior even though the ferroelectric polarization is small in comparison to that of other ferroelectrics.
TL;DR: In this paper, the authors observed a sizable positive magnetocapacitance in perovskite and bilayer systems under 5T magnetic field across 20-100 K below the magnetic transition point T$_N.
Abstract: We have observed a sizable positive magnetocapacitance ($\sim$$5-90\%$) in perovskite Pr$_{0.55}$Ca$_{0.45}$MnO$_3$ and bilayer Pr(Sr$_{0.1}$Ca$_{0.9}$)$_2$Mn$_2$O$_7$ system under 5T magnetic field across 20-100 K below the magnetic transition point T$_N$. The magnetodielectric effect, on the other hand, exhibits a crossover: (a) from positive to negative for the perovskite system and (b) from negative to positive for the bilayer system over the same temperature range. The bilayer Pr(Sr$_{0.1}$Ca$_{0.9}$)$_2$Mn$_2$O$_7$ system exhibits a sizable anisotropy as well. We have also noticed the influence of magnetic field on the dielectric relaxation characteristics of these systems. These systems belong to a class of improper ferroelectrics and are expected to exhibit charge/orbital order driven ferroelectric polarization below the transition point T$_{CO}$. Large magnetocapacitance in these systems shows typical multiferroic behavior even though the ferroelectric polarization is small in comparison to that of other ferroelectrics.
TL;DR: In this article, the specific heat, magnetization, and magnetocapacitance of YbMnO3 and Ybmn0.7Ga0.3O3 multiferroic single crystal manganites were measured in magnetic field.
Abstract: The specific heat, magnetization, and magnetocapacitance of YbMnO3 and YbMn0.7Ga0.3O3 multiferroic single crystal manganites were measured in magnetic field. From the specific heat data it was stated that the effect of dilution of Mn by non-magnetic Ga3+ ions led to reduced Mn magnetic interactions and suppressed the magnetic ordering of Yb in both the 2a and 4b positions. Combining the results of all measurements, the magnetic-field–temperature phase diagram YbMnO3 was drawn, and the types of the Yb magnetic ordering in both positions were determined.
04 Dec 2013
TL;DR: In this paper, an inhomogeneous model was used to explain the change in resistivity of nanostructures in the presence of oxygen vacancies as a result of large surface area present.
Abstract: Silver nanoparticles of diameters 3.4 to 13.2 nm grown at the interfaces between silicate glass and some oxide crystallites exhibited about six orders of magnitude reduction in resistivity for a relative humidity change from 25% to 80%. Sn-SnO2 nano core-shell structure prepared within a gel-derived silica glass film by electrodeposition technique followed by heat treatment showed large change in resistivity as a function of humidity. The resistivity also changed due to gas flow of CO2, C2H5OH and NO2, respectively. The latter arose because of reduction/oxidation of Sn4+/Sn2+ species present at the shell layer of the nanostructures. Nickel nanosheets of thickness ~0.6 nm grown within the interlayer spaces of Na-4 mica crystallites showed a change of dielectric permittivity (5%) for an applied magnetic field of 1.2 Tesla. An inhomogeneous model was used to explain this behavior. Two dimensional CuO phase was grown within the channels of diameter ~5 nm of mesoporous SiO2 structure. A magnetodielectric (MD) parameter M.D. of 4.4% was obtained in this case. BaTiO3 nanoparticles of diameter ~25 nm having pores with diameter 10 nm showed multiferroic behavior which arose due to the presence of oxygen vacancies as a result of large surface area present. An M.D. parameter of 11% was found. Similarly mesoporous LiNbO3 of 10 nm diameter showed an M.D. parameter of ~4.5% at a magnetic field 1 Tesla. A giant magnetocapacitance effect with a value of 44% at 1.5 T was observed in nickel zinc ferrite (NZF) impregnated mesoporous silica. A magnetocapacitance of 51% at magnetic field 1.7 T was found in the case of nanocomposites comprising of iron ion containing silica based nanoglass and mesoporous silica. In the last two examples the behavior was explained on the basis of Catalan model of space-charge polarization with extracted values of magnetoresistance of the NZF and nanoglass phases being 58%.
TL;DR: In this paper, the junction capacitance and voltage characteristics of highly textured/epitaxial Ni nanoparticle embedded in TiN matrix (TiN(Ni)) metal-insulator-semiconductor TiN/SiO2/p-Si (100) heterojunction in the temperature range of 10-300
Abstract: This work presents the junction capacitance–voltage characteristics of highly textured/epitaxial Ni nanoparticle embedded in TiN matrix (TiN(Ni)) metal-insulator-semiconductor TiN(Ni)/SiO2/p-Si (100) heterojunction in the temperature range of 10–300 K. This heterojunction behaves as metal-semiconductor junction with unavoidable leakage through native oxide SiO2 layer. The clockwise hysteresis loop has been observed in the capacitance-voltage characteristics measured at various frequencies mainly due to presence of trap centers at the TiN(Ni)/SiO2 interface and these are temperature dependent. The spin-dependent trap charge effect at the interface influences the quadratic nature of the capacitance with magnetic field. The junction magnetocapacitance (JMC) is observed to be dependent on both temperature and frequency. The highest JMC of this heterojunction has been observed at 200 K at higher frequencies (100 kHz–1 MHz). It is found that there is not much effect of band structure modification under magnetic field causing the JMC.
TL;DR: In this article, a theoretical study of the quantum magnetocapacitance of an ultrathin topological insulator film in an external magnetic field was carried out and the interplay of the Zeeman interaction with the hybridization between the upper and lower surfaces of the thin film was investigated.
Abstract: We present a theoretical study of the quantum magnetocapacitance of an ultrathin topological insulator film in an external magnetic field. The study is undertaken to investigate the interplay of the Zeeman interaction with the hybridization between the upper and lower surfaces of the thin film. Determining the density of states, we find that the electron-hole symmetry is broken when the Zeeman and hybridization energies are varied relative to each other. This leads to a change in the character of the magnetocapacitance at the charge neutrality point. We further show that in the presence of both Zeeman interaction and hybridization the magnetocapacitance exhibits beating at low and splitting of the Shubnikov de Haas oscillations at high perpendicular magnetic field. In addition, we address the crossover from perpendicular to parallel magnetic field and find consistency with recent experimental data.