Heavy Band Research Articles

Excitonic effects on electron spin orientation and relaxation in wurtzite GaN

Excitonic effects on electron spin orientation and relaxation in wurtzite GaN are investigated with photon-energy-dependent time-resolved Kerr rotation spectroscopy at low temperatures. It is observed that the spin orientation generated with circularly polarized light can be manipulated with photon energy upon the excitation energy being resonated with various fine energy levels in the band structure. Three reversals of the spin orientation and a remarkable reduce of spin relaxation time are obtained, which is caused by the photon-energy dependent transitions from the heavy and light hole bands to the exciton levels and the conduction band edge. A long spin relaxation time of 1.7 ns is attributed to the spin polarization of donor-bound electrons as the formation of donor-bound excitons, while the spin relaxation time of the conduction band electrons is shorter and shows a nonmonotonic dependence on the optical excitation power, revealing the dominant role of the D'yakonov-Perel' spin relaxation mechanism in wurtzite GaN.

Photoemission signature of momentum-dependent hybridization in CeCoIn5

Hybridization between $f$ electrons and conduction bands ($c$-$f$ hybridization) is a driving force for many unusual phenomena. To provide insight into it, systematic studies of CeCoIn$_5$ heavy fermion superconductor have been performed by angle-resolved photoemission spectroscopy (ARPES) in a large angular range at temperature of $T=6$ K. The used photon energy of 122 eV corresponds to Ce $4d$-$4f$ resonance. Calculations carried out with relativistic multiple scattering Korringa-Kohn-Rostoker method and one-step model of photoemission yielded realistic simulation of the ARPES spectra indicating that Ce-In surface termination prevails. Surface states, which have been identified in the calculations, contribute significantly to the spectra. Effects of the hybridization strongly depend on wave vector. They include a dispersion of heavy electrons and bands gaining $f$-electron character when approaching Fermi energy. We have also observed a considerable variation of $f$-electron spectral weight at $E_F$, which is normally determined by both matrix element effects and wave vector dependent $c$-$f$ hybridization. Fermi surface scans covering a few Brillouin zones revealed large matrix element effects. A symmetrization of experimental Fermi surface, which reduces matrix element contribution, yielded a specific variation of $4f$-electron enhanced spectral intensity at $E_F$ around $\bar{\Gamma}$ and $\bar{M}$ points. Tight-binding approximation calculations for Ce-In plane provided the same universal distribution of $4f$-electron density for a range of values of the parameters used in the model.

Optimizing Electronic Quality Factor toward High‐Performance Ge1−x−yTaxSbyTe Thermoelectrics: The Role of Transition Metal Doping

AbstractOwing to high intrinsic figure‐of‐merit implemented by multi‐band valleytronics, GeTe‐based thermoelectric materials are promising for medium‐temperature applications. Transition metals are widely used as dopants for developing high‐performance GeTe thermoelectric materials. Herein, relevant work is critically reviewed to establish a correlation among transition metal doping, electronic quality factor, and figure‐of‐merit of GeTe. From first‐principle calculations, it is found that Ta, as an undiscovered dopant in GeTe, can effectively converge energy offset between light and heavy conduction band extrema to enhance effective mass at high temperature. Such manipulation is verified by the increased Seebeck coefficient of synthesized Ge1−x−yTaxSbyTe samples from 160 to 180 µV K−1 at 775 K upon doping Ta, then to 220 µV K−1 with further alloying Sb. Characterization using electron microscopy also reveals the unique herringbone structure associated with multi‐scale lattice defects induced by Ta doping, which greatly hinder phonon propagation to decrease thermal conductivity. As a result, a figure‐of‐merit of ≈2.0 is attained in the Ge0.88Ta0.02Sb0.10Te sample, reflecting a maximum heat‐to‐electricity efficiency up to 17.7% under a temperature gradient of 400 K. The rationalized beneficial effects stemming from Ta doping is an important observation that will stimulate new exploration toward high‐performance GeTe‐based thermoelectric materials.

Superconducting fluctuations and giant negative magnetoresistance in a gate-voltage tuned two-dimensional electron system with strong spin-orbit impurity scattering

We present a quantitative theory of the gate-voltage tuned superconductor-to-insulator transition (SIT) observed experimentally in the 2D electron system created in the (111) interface between crystalline ${\mathrm{Sr}\mathrm{Ti}\mathrm{O}}_{3}$ and ${\mathrm{La}\mathrm{Al}\mathrm{O}}_{3}$. Considering two fundamental opposing effects of Cooper-pair fluctuations---the critical conductivity enhancement, known as paraconductivity, and its suppression associated with the loss of unpaired electrons due to Cooper-pairs formation---we generalize the standard thermal fluctuations theory to include interaction between fluctuations within the self-consistent field approximation and quantum tunneling between mesoscopic superconducting puddles within a phenomenological approach. Relying on the quantitative agreement found between our theory and a large body of experimental sheet-resistance data, we conclude that spin-orbit scatterings, via significant enhancement of the interaction between fluctuations, strongly enhance the sheet resistance peak at high fields and reveal anomalous metallic behavior at low fields, due to mixing of relatively heavy electron bands with a light electron band near a Lifshitz point. The large enhancement of the interaction between fluctuations at high fields, where the sheet resistance is strongly amplified, is shown to result in localization of Cooper-pair fluctuations within mesoscopic puddles.

Structural changes of meat protein of chicken sausages with various levels of salt and phosphate and their effects on in vitro digestion

SummaryThe objectives of this study were to evaluate protein oxidation and in vitro digestibility of chicken sausages with various salt/phosphate combinations. Hydrophobicity increased when protein was cooked and denatured (P < 0.05). Protein oxidation was increased based on levels of SH, S‐S and carbonyl groups during the cooking process (P < 0.05). Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE) revealed that the intensity of myosin heavy chain band was decreased while biopolymer band was denser when sausages were cooked. Sausages with 1.8% salt and 0.3% phosphate (S1P1) showed the lowest digestibility and maintained a flat and compact structure, unlike other treatments during the gastrointestinal digestive stage. SDS‐PAGE of digested chicken sausages showed that protein bands were degraded into small bands followed by gradual disappearance. In conclusion, cooking process can lead to protein denaturation and oxidation, regardless of levels of salt and phosphate added. In addition, adding salt and phosphate can significantly affect the digestibility of meat products.

Origin of charge density wave in the kagome metal CsV3Sb5 as revealed by optical spectroscopy

We report on a detailed study of the optical properties of CsV$_{3}$Sb$_{5}$ at a large number of temperatures above and below the charge-density-wave (CDW) transition. Above the CDW transition, the low-frequency optical conductivity reveals two Drude components with distinct widths. An examination of the band structure allows us to ascribe the narrow Drude to multiple light and Dirac bands, and the broad Drude to the heavy bands near the $M$ points which form saddle points near the Fermi level. Upon entering the CDW state, the opening of the CDW gap is clearly observed. A large portion of the broad Drude is removed by the gap, whereas the narrow Drude is not affected. Meanwhile, an absorption peak associated with interband transitions near the saddle points shifts to higher energy and grows in weight. These observations are consistent with the scenario that the CDW in CsV$_{3}$Sb$_{5}$ is driven by nesting of Fermi surfaces near the saddle points at $M$.

High-energy magnetic excitations from heavy quasiparticles in CeCu2Si2

Magnetic fluctuations is the leading candidate for pairing in cuprate, iron-based, and heavy fermion superconductors. This view is challenged by the recent discovery of nodeless superconductivity in CeCu2Si2, and calls for a detailed understanding of the corresponding magnetic fluctuations. Here, we mapped out the magnetic excitations in superconducting (S-type) CeCu2Si2 using inelastic neutron scattering, finding a strongly asymmetric dispersion for E ≲ 1.5 meV, which at higher energies evolves into broad columnar magnetic excitations that extend to E ≳ 5 meV. While low-energy magnetic excitations exhibit marked three-dimensional characteristics, the high-energy magnetic excitations in CeCu2Si2 are almost two-dimensional, reminiscent of paramagnons found in cuprate and iron-based superconductors. By comparing our experimental findings with calculations in the random-phase approximation,we find that the magnetic excitations in CeCu2Si2 arise from quasiparticles associated with its heavy electron band, which are also responsible for superconductivity. Our results provide a basis for understanding magnetism and superconductivity in CeCu2Si2, and demonstrate the utility of neutron scattering in probing band renormalization in heavy fermion metals.

Entropy engineering promotes thermoelectric performance in p-type chalcogenides

We demonstrate that the thermoelectric properties of p-type chalcogenides can be effectively improved by band convergence and hierarchical structure based on a high-entropy-stabilized matrix. The band convergence is due to the decreased light and heavy band energy offsets by alloying Cd for an enhanced Seebeck coefficient and electric transport property. Moreover, the hierarchical structure manipulated by entropy engineering introduces all-scale scattering sources for heat-carrying phonons resulting in a very low lattice thermal conductivity. Consequently, a peak zT of 2.0 at 900 K for p-type chalcogenides and a high experimental conversion efficiency of 12% at ΔT = 506 K for the fabricated segmented modules are achieved. This work provides an entropy strategy to form all-scale hierarchical structures employing high-entropy-stabilized matrix. This work will promote real applications of low-cost thermoelectric materials.

Non-lethal screening of Asian seabass (Lates calcarifer) by monoclonal antibody based indirect enzyme linked immunosorbent assay for viral nervous necrosis

Viral nervous necrosis (VNN) is a serious viral disease of several species of farmed and wild fishes. Adult fish are asymptomatic and become carriers of the virus when infected with nervous necrosis virus (NNV) and they transmit the virus to the offspring through eggs. ELISA is ideal for non-lethal screening of adult fish for VNN. Asian seabass (Lates calcarifer) IgM was purified using Protein A affinity column and hybridoma clones secreting monoclonal antibodies (MAb) specific to the heavy chain of IgM was developed. An Indirect ELISA using anti-seabass IgM MAb was developed by optimizing all the reagents. The assay was used to screen adult Asian seabass from grow-out farms in comparison to RT-PCR. The assay was also used to assess the immune response in Asian seabass immunized with inactivated Red-spotted grouper NNV (RGNNV). Seabass IgM on SDS-PAGE analysis revealed three heavy chain bands of size 96, 82 and 76 kDa and a single light chain of size 25 kDa. Out of 18 positive hybridoma clones, two selected clones reacted specifically with the 76 kDa heavy chain band. Out of 28 serum samples of Asian seabass from grow-out farms 26 were positive for NNV antibodies while 22 were positive by RT-PCR. Fish immunized with inactivated RGNNV showed immune response by one week post-immunization, and the peak immune response was observed four weeks post-immunization. The assay developed can be used for non-lethal screening of adult Asian seabass for VNN and to assess the immune response after vaccination.

Do Metabolic Enzymes Explain Osmoregulation in Juvenile American Eels

During the spring, juvenile eels (Anguilla rostrata) (5-6 cm; 50-200 mg) gather in creeks along the Hudson River Tributary Estuary after migration from the Atlantic Ocean. This requires them to quickly adapt to environments with lower salt concentrations. We wondered how this is achieved. To study eels in a lab setting, we transferred them into Instant Ocean® sea salt (100% artificial sea water [ASW]) or dilutions thereof for 2 weeks; mortality was only observed in 100% ASW (37% expired in 3 hours). Interestingly, after 4 hours, 10 or 50% ASW eels showed little change in body mass, suggesting osmoregulation. While much progress has been made in understanding the mature eel response, few studies have reported enzyme activities in young eels. We hypothesized that dehydrogenases and acetylcholine esterase activities might provide a clue to explain osmoregulation and survival. Supernatants of whole juvenile eel extracts obtained from these experiments (IACUC-approved protocol) were run on 7.5% Tris-glycine PAGE gel (150V, 50 min) and the activities of non–denatured isozyme bands were analyzed with Bio-Rad ChemiDoc™ XRS+ Imager. Denatured supernatant extracts were also run on TGX 4-15% Tris-glycine PAGE gel to assess total protein banding. There was little difference in number of protein bands between eels exposed to 10% vs 50% ASW(2 and 3 weeks); however, band intensities were significantly higher for 50% ASW. Further studies revealed that two MDH (malate dehydrogenase) isozyme bands were present in extracts of eels exposed to a broad range of salinities: a relatively heavier band as mitochondrial (m) MDH and a lighter cytoplasmic (c) MDH. Activities of the mMDH bands were more robust than the cMDH bands at 50% and 10% ASW. Although the mMDH activities in eels exposed to either salinity were similar, the cMDH activities in eels exposed to 50% ASW were greater than in eels exposed to 10%. Additional experiments identified four acetylcholine esterase (AChE) isozyme bands in eel extracts; the activity of only one was significantly prominent in all exposures. Transferring the eels from 50% to 10% ASW reduced activity of the relatively heaviest isozyme band. Notably, we could not discern any fluctuations in lactate dehydrogenase (LDH) levels. In conclusion, while these preliminary findings do not reveal any concrete trends in metabolic regulation tied to survival, it does appear several key enzymes have a translational correlation tied to saline homeostasis. We acknowledge that the interpretation of these experimental results is complicated by a lack of genetic validation (i.e., sequences information and parental lines) - “nature” . In addition, the investigators were unable to track or define the environmental stresses faced during migration by individual juvenile eels before capture, which may manifest itself in unique stress responses - “nurture.”

Versatile Vanadium Doping Induces High Thermoelectric Performance in GeTe via Band Alignment and Structural Modulation

AbstractOwing to the moderate energy offset between light and heavy band edges of the rock‐salt structured GeTe, its figure‐of‐merit (ZT) can be enhanced by the rational manipulation of electronic band structures. In this study, density functional theory calculations are implemented to predict that V is an effective dopant for GeTe to enlarge the bandgap and converge the energy offset, which suppresses the bipolar conduction and increases the effective mass. Experimentally, V‐doped Ge1−xVxTe samples are demonstrated to have an enhanced Seebeck coefficient from ≈163 to ≈191 µV K−1. Extra alloying with Bi in Ge1−x−yVxBiyTe can optimize the carrier concentration to further enhance the Seebeck coefficient up to ≈252 µV K−1, plus an outstanding power factor of ≈43 µW cm−1 K−2. Comprehensive structural characterization results also verify the refinement of grain size by V‐doping, associated with highly dense grain boundaries, stacking faults, nanoprecipitates, and point defects, reinforcing the wide‐frequency phonon scattering and in turn, securing an ultralow thermal conductivity of ≈0.59 W m−1 K−1. As a result, the Ge0.9V0.02Bi0.08Te sample shows a peak ZT of >2.1 at 773 K, with an average plateaued average ZT of >2.0 from 623 and 773 K, which extends better thermoelectric behavior for GeTe over a wider temperature range. This study clarifies the multiple benefits of V‐doping in GeTe‐based derivatives and provides a framework for a new‐type of high‐performance middle‐temperature thermoelectric material.

The Devil’s Music: Satanism and Christian Rhetoric in the Lyrics of the Swedish Heavy Metal Band Ghost

This paper is an inquiry into a contemporary heavy metal band from Sweden called Ghost. Ghost released its first studio album in 2010 and, while there is some discussion as to what their genre is exactly, they immediately became a rising star in the metal scene. Yet what is of particular interest from a storytelling point of view, especially with regard to theological answers to philosophical questions in popular culture, is that the band presents itself as a satanic version of the Catholic Church through their stage act and lyrics. This made me curious whether they are trying to convey a message and, if yes, what that message might be. For the present paper, I have focused on the latter by performing a non-exhaustive textual analysis of the lyrics in a selection of songs from each of the four studio albums released so far. Ghost turns Christian liturgy on its head by utilizing devout language that is normally reserved for God and Christ to describe Satan and the Antichrist, a strategy I have called the ”satanification” of Christian doctrine, and in doing so their songs evoke imagery of a satanic faith community at prayer. The band then uses this radical inversion of traditional Christian themes to criticize certain elements of society, especially those aspects they associate with organized religion.

UTe2 : A nearly insulating half-filled j=52 5f3 heavy-fermion metal

Correlated band theory implemented as a combination of density functional theory with exact diagonalization [$\mathrm{DFT}+U$(ED)] of the Anderson impurity term with Coulomb repulsion $U$ in the open 14-orbital $5f$ shell is applied to ${\mathrm{UTe}}_{2}$. The small gap for $U=0$, evidence of the half-filled $j=\frac{5}{2}$ subshell of $5{f}^{3}$ uranium, is converted for $U=3\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ to a flat-band semimetal with small heavy-carrier Fermi surfaces that will make properties sensitive to pressure, magnetic field, and off-stoichiometry, as observed experimentally. Two means of identification from the Green's function give a mass enhancement of the order of 12 for already heavy (flat) bands, consistent with the common heavy-fermion characterization of ${\mathrm{UTe}}_{2}$. The predicted Kondo temperature around 100 K matches the experimental values from resistivity. The electric field gradients for the two Te sites are calculated by $\mathrm{DFT}+U$(ED) to differ by a factor of 7, indicating a strong site distinction, while the anisotropy factor $\ensuremath{\eta}=0.18$ is similar for all three sites. The calculated uranium moment ${\ensuremath{\langle}{M}^{2}\ensuremath{\rangle}}^{1/2}$ of $3.5\phantom{\rule{0.28em}{0ex}}{\ensuremath{\mu}}_{B}$ is roughly consistent with the published experimental Curie-Weiss values of 2.8 and $3.3\phantom{\rule{0.28em}{0ex}}{\ensuremath{\mu}}_{B}$ (which are field-direction dependent), and the calculated separate spin and orbital moments are remarkably similar to Hund's rule values for an ${f}^{3}$ ion. The $U=3\phantom{\rule{0.28em}{0ex}}\mathrm{eV}$ spectral density is compared with angle-integrated and angle-resolved photoemission spectra, with agreement that there is strong $5f$ character at, and for several hundred meV below, the Fermi energy. Our results support the picture that the underlying ground state of ${\mathrm{UTe}}_{2}$ is that of a half-filled $j=\frac{5}{2}$ subshell with two half-filled ${m}_{j}=\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ orbitals forming a narrow gap by hybridization and then driven to a conducting state by configuration mixing (spin-charge fluctuations). ${\mathrm{UTe}}_{2}$ displays similarities to ${\mathrm{UPt}}_{3}$ with its $5f$-dominated Fermi surfaces rather than a strongly localized Kondo lattice system.

Determinants of the number of heavy metal musicians per capita

This study is a follow-up to the 2015 study titled ‘Determinants of the production of heavy metal music’. That study attempted to find an equation that would predict the number of heavy metal bands that each country had. That study was unable to arrive at a single equation, and double counting the output of musicians who were in more than one band was likely the reason. This study re-tests the variables that were found to be significant in the original study, some alternatives to those variables, and reconsiders some variables that were not found to be significant in the original study. To overcome the problem that the original study had with double counting the output of musicians who were in more than one band, this study uses the number of metal musicians per 100,000 people as the dependent variable rather than the number of heavy metal bands per 100,000 people. The independent variables considered in this study are as follows: the percentage of population with access to electricity, the number of unpaid parking tickets per UN diplomat during the period in which the City of New York was not enforcing parking violations on diplomats, the number of concert halls per million population, the Democracy Index, the percentage of the population who speak English, per capita electrical consumption, the average GDP per capita for the prior 3 years, the GINI index, latitude, life expectancy, Scandinavian Law, the average number of years of school that a citizen is expected to complete, the number of years the country was governed under constitutions that made reference to Marxism (with several variants capping the number of years at 20, 30, 40, 50 and 60), males between the ages of 15 and 24 as a percentage of the total population, males between the ages of 15 and 24 as a percentage of all males, the percentage of the population that identifies as Catholic and the percentage of the population that is not affiliated with a religion. The study found that changing the dependent variable from the number of metal bands per 100,000 to the number of metal musicians per 100,000 people did address the problem of double counting the output of some musicians; the original study was unable to arrive at a single equation as a model, this study was able to do that. This study and the original study arrived at the same significant independent variables: the number of concert halls per million population, latitude, Scandinavian law, Years Marxist, males between the ages of 15 and 24 as a percentage of the total population, the percentage of the population that identifies as Catholic and the percentage of the population that is not affiliated with a religion.

Gutzwiller hybrid quantum-classical computing approach for correlated materials

Rapid progress in noisy intermediate-scale quantum (NISQ) computing technology has led to the development of novel resource-efficient hybrid quantum-classical algorithms, such as the variational quantum eigensolver (VQE), that can address open challenges in quantum chemistry, physics and material science. Proof-of-principle quantum chemistry simulations for small molecules have been demonstrated on NISQ devices. While several approaches have been theoretically proposed for correlated materials, NISQ simulations of interacting periodic models on current quantum devices have not yet been demonstrated. Here, we develop a hybrid quantum-classical simulation framework for correlated electron systems based on the Gutzwiller variational embedding approach. We implement this framework on Rigetti quantum processing units (QPUs) and apply it to the periodic Anderson model, which describes a correlated heavy electron band hybridizing with non-interacting conduction electrons. Our simulation results quantitatively reproduce the known ground state quantum phase diagram including metallic, Kondo and Mott insulating phases. This is the first fully self-consistent hybrid quantum-classical simulation of an infinite correlated lattice model executed on QPUs, demonstrating that the Gutzwiller hybrid quantum-classical embedding framework is a powerful approach to simulate correlated materials on NISQ hardware. This benchmark study also puts forth a concrete pathway towards practical quantum advantage on NISQ devices.

Influence of stewing conditions on tenderness and protein structure in beef

In this study, the effects of heating temperature (70°C ~ 100°C) and time (0 ~ 180 min) on beef M. longissimus dorsi tenderness, the oxidation characteristics of myofibrillar protein (MP), and the correlation between tenderness with protein oxidation characteristics were studied. The results showed that heating temperature and time significantly influenced beef tenderness and MP oxidation characteristics. SDS-PAGE analysis indicated that the thermal stability of actin was significantly higher than that of myosin heavy chain. Myosin heavy chain bands disappeared completely when heated for 120 min at 90°C or for 30 min at 100°C. The actin bands faded slightly and they were still clearly visible when heated for 180 min at 100°C. Correlation analysis showed that beef shear force value was significant negatively correlated with the dityrosine content (p < .01). This will provide a theoretical basis for the quality control and cooking process optimization of Chinese traditional beef stew dishes. Novelty impact statement This study investigated the changes of beef tenderness and myofibrillar protein structure during stewing and elucidated the correlation between beef tenderness and myofibrillar protein structure. The results will provide a theoretical basis for the quality control and cooking process optimization of Chinese traditional beef stew dishes.

Is Metallica Fractal? A Case Study

The heavy metal band Metallica’s performance history provides evidence for a particular theory of how power law distributions in data are formed.

Effective mass of heavy, light, and spin split-off band electron and hole g-factor in cubic perovskite materials

Analytical expressions for the effective mass of heavy, light, and spin split-off electrons are obtained by diagonalizing the k⋅p Hamiltonian for cubic perovskite crystal structures and used to calculate these in nine perovskite materials. An expression for the effective hole g-factor is also derived and calculated in these perovskites. The calculated effective mass of heavy electrons ranges from 1.619 m0 to 0.201 m0, of light electrons from 0.357 m0 to 0.146 m0, and of spin split-off electrons from 0.584 m0 to 0.169 m0. It is found that Cl- and Pb-based perovskite materials have larger heavy, light, and spin split-off electron effective masses. It is also found that the effective g-factor increases with the atomic size, from Cl to I, for the series CsSnX3(X=Cl,Br,I).

Lifshitz transition underlying the metamagnetic transition of UPt3

Comparing quantum oscillation measurements, dc magnetoresistance measurements, and Fermi surfaces obtained from LDA calculations, we argue that the metamagnetic transition of UPt3, which occurs at an applied field μ ◦ H M ∼ 20 T, coincides with a Lifshitz transition at which an open orbit on the band 2 hole-like Fermi surface becomes closed for one spin direction. At low field, proximity of the Fermi energy to this particular van Hove singularity may have implications for the superconducting pairing potential of UPt3. In our picture the magnetization comes from non-linear spin-splitting of the heavy fermion bands. In support of this, we show that the non-linear field dependence of a particular quantum oscillation frequency can be fitted by assuming that the corresponding extremal Fermi surface area is proportional to the magnetization. In addition, below H M , we find in our LDA calculations a new, non-central orbit on band 1, whose non-linear behaviour explains a field-dependent frequency recently observed in magnetoacoustic quantum oscillation measurements.

On the applicability of the single parabolic band model to advanced thermoelectric materials with complex band structures

Due to the complex interplay between composition, synthesis parameters and the performance of thermoelectric materials, the optimization of thermoelectric materials needs to be complemented by modelling. A relatively simple and thus popular approach is the so called single parabolic band model, which allows for an efficient optimization of the material properties and a benchmarking of different materials based on relatively few, well available experimental results. As complex band structures are common for high performance materials, single parabolic band modelling is also employed with apparent success for material systems where the underlying assumptions are not well fulfilled. In order to assess the validity of a single parabolic band analysis for such systems, the thermoelectric properties for two model systems are calculated: one with a single band that is twofold degenerate and one with a light and a heavy band. Even if the density of states masses and the scattering potentials are kept identical, the transport properties and in particular the Hall coefficients differ significantly, which leads to an incorrectly determined carrier concentration. As the carrier concentration is the base for the single parabolic band analysis, all the quantities obtained from it (optimum carrier concentration, effective mass, deformation potential) are determined incorrectly as well.