The German twin family study 'TwinLife' was designed to enhance our understanding of the development of social inequalities over the life course. The interdisciplinary project investigates mechanisms of social inequalities across the lifespan by taking into account psychological as well as social mechanisms, and their genetic origin as well as the interaction and covariation between these factors. Main characteristics of the study are: (1) a multidimensional perspective on social inequalities, (2) the assessment of developmental trajectories in childhood, adolescence, and young adulthood in a longitudinal design by using (3) a combination of a multi-cohort cross-sequential and an extended twin family design, while (4) capturing a large variation of behavioral and environmental factors in a representative sample of about 4,000 German twin families. In the present article, we first introduce the theoretical and empirical background of the TwinLife study, and second, describe the design, content, and implementation of TwinLife. Since the data will be made available as scientific use file, we also illustrate research possibilities provided by this project to the scientific community.

We have performed continuous wave and pulsed electron spin resonance measurements of implanted bismuth donors in isotopically enriched silicon-28. Donors are electrically activated via thermal annealing with minimal diffusion. Damage from bismuth ion implantation is repaired during thermal annealing as evidenced by narrow spin resonance linewidths (Bpp = 12 µT) and long spin coherence times (T2 = 0.7 ms, at temperature T = 8 K). The results qualify ion implanted bismuth as a promising candidate for spin qubit integration in silicon.Electron and nuclear spins of donor atoms in silicon are excellent qubit candidates for quantum information processing [1, 2]. Isotope engineered substrates provide a nuclear spin free host environment, resulting in long electron and nuclear spin coherence times of several seconds [3,4]. Spin properties of donor qubit candidates in silicon have been studied mostly for phosphorous and antimony [3][4][5][6]. Bismuth donors in silicon are unique in exhibiting a relatively large zero field splitting of 7.4 GHz. Thus, they have attracted attention as potential nuclear spin memory and spin qubit candidates [7,8] that could be coupled to superconducting resonators [7,9,10]. Bismuth is the deepest donor in silicon with a binding energy of 70 meV and a corresponding small Bohr radius. The small Bohr radius and bismuth's reduced effective gyromagnetic ratio [7] can make it less susceptible to interface noise at a given implant depth and make bismuth very desirable for quantum logic implementation via magnetic dipolar coupling [11]. Furthermore, bismuth is also the heaviest donor in silicon and thus shows the least ion range straggling during ion implantation, which enables for donor qubit placement with high spatial resolution [12,13].To date, studies of spin resonance properties of bismuth in silicon have been performed with bulk doped natural silicon [7,8,[14][15][16] whereas silicon-28 material is preferable for improved spin coherence properties. Electrical activation of implanted bismuth via thermal anneals has been studied for relatively high implant doses [17][18][19][20][21], and concentrations close to the the metalinsulator transition (N c = 1.7 × 10 19 cm −3 ) [18]. High implant doses ( 1 × 10 14 cm −2 for keV Bi-ions at room temperature) amorphize the silicon lattice [22]. Solid- * Please contact the corresponding author under cdweis@lbl.gov phase epitaxial regrowth (SPER) can be used to prevent diffusion of bismuth atoms and incorporate them on substitutional sites. This can lead to electrically active concentrations well above the low relatively solubility limit of bismuth in silicon (which is, e.g. 2.3 × 10 17 cm −3 at 1150 ℃ [23]). For SPER, thermal anneals at low temperatures, e.g. few minutes at 600 ℃ yield electrical activation levels of up to 90 % [20]. For low implant doses and dopant concentrations, which are desirable for long spin coherence times, no amorphization of the silicon crystal occurs during ion implantation. Thus, the electrical activation levels and annealing ...

The relative importance of genes and shared environmental influences on stratification outcomes has recently received much attention in the literature. We focus on education and the gene-environmental interplay. Specifically, we investigate whether-as proposed by the Scarr-Rowe hypothesis-genetic influences are more important in advantaged families. We argue that the social stratification of family environments affects children's chances to actualize their genetic potential. We hypothesize that advantaged families provide more child-specific inputs, which enhance genetic expression, whereas the rearing environments of children in disadvantaged families are less adapted to children's individual abilities, leading to a suppression of genetic potential. We test this relationship in Germany, which represents an interesting case due to its highly selective schooling system characterized by early tracking and the broad coverage of part-time schools. We use novel data from the TwinLife panel, a population-register-based sample of twins and their families. Results of ACE-variance decompositions support the Scarr-Rowe hypothesis: Shared environmental influences on education matter only in disadvantaged families, whereas genetic influences are more important in advantaged families. Our findings support the growing literature on the importance of the gene-environmental interplay and emphasize the role of the family environment as a trigger of differential genetic expression.

We present a systematical experimental investigation of an unusual transport phenomenon observed in two dimensional electron gases in Si/SiGe heterostructures under integer quantum Hall effect (IQHE) conditions. This phenomenon emerges under specific experimental conditions and in different material systems. It is commonly referred to as Hall resistance overshoot, however, lacks a consistent explanation so far. Based on our experimental findings we are able to develop a model that accounts for all of our observations in the framework of a screening theory for the IQHE. Within this model the origin of the overshoot is attributed to a transport regime where current is confined to co-existing evanescent incompressible strips of different filling factors.

We have measured the electrically detected magnetic resonance of channel-implanted donors in silicon field-effect transistors in resonant X-(9.7 GHz) and W-band (94 GHz) microwave cavities, with corresponding Zeeman fields of 0.35 T and 3.36 T, respectively. It is found that the conduction electron resonance signal increases by two orders of magnitude from X-to W-band, while the hyperfine-split donor resonance signals are enhanced by over one order of magnitude. We rule out a bolometric origin of the resonance signals, and find that direct spin-dependent scattering between the two-dimensional electron gas and neutral donors is inconsistent with the experimental observations. We propose a new polarization transfer model from the donor to the conduction electrons as the main contributer to the spin resonance signals observed.Electrical spin-state detection for solid-state qubits requires a detection channel formed by conduction electrons in close proximity to the qubit. For electron spin qubits, the detection channels usually consist of quantum point contacts or single electron transistors, which are sensitive to the electrostatic environment nearby and able to detect the spin-dependent occupancies of electrons at the qubit site [1][2][3][4]. Alternatively, for nuclear spin qubits such as shallow donors in silicon [5], it was proposed that conduction electrons interacting directly with the neutral donors can be used for nuclear spin-state readout [6], as the conduction and neutral donor electrons undergo spindependent scattering [7][8][9][10][11]. Donor-doped metal-oxidesemiconductor (MOS) devices provide an ideal platform for the detection of such an interaction, as the electronic wavefunction of neutral donors embedded in the device channel can overlap with the nearby gate-induced twodimensional electron gas (2DEG) (Fig. 1(a)). The donor-2DEG interaction can be probed by electrically detected magnetic resonance (EDMR) experiments with the MOS system, as was first reported by Ghosh and Silsbee [7]. However, the use of bulk-doped silicon with a relatively high donor concentration resulted in significant overlap between the donor and 2DEG electron resonance signals, complicating the analysis of the results. In addition, their measurements were limited to a low magnetic field of ∼ 0.35 T. In this Letter, we clarify the mechanisms behind the EDMR signals of such donordoped MOS devices by studying the change in EDMR signal intensities at different magnetic fields. We perform EDMR with accumulation-mode n-type field-effect * Both authors contributed to this work equally. Please contact the corresponding author under cclo@eecs.berkeley.edu.

Controlled nanoscale self-assembly of magnetic entities in semiconductors opens novel perspectives for the tailoring of magnetic semiconductor films and nanostructures with room temperature functionality. We report that a strongly directional self-assembly in growth direction in Mn-alloyed Ge is due to a stacking of individual Ge(1-x)Mn(x) clusters. The clusters represent the relevant entities for the magnetization of the material. They are formed of a core-shell structure displaying a Mn concentration gradient. While the magnetic moments seem to be carried by the shells of the clusters, their core is magnetically inactive.

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There is a growing interest in how social conditions moderate genetic influences on education [gene–environment interactions (GxE)]. Previous research has focused on the family, specifically parents’ social background, and has neglected the institutional environment. To assess the impact of macro-level influences, we compare genetic influences on educational achievement and their social stratification across Germany, Norway, Sweden, and the United States. We combine well-established GxE-conceptualizations with the comparative stratification literature and propose that educational systems and welfare-state regimes affect the realization of genetic potential. We analyse population-representative survey data on twins (Germany and the United States) and twin registers (Norway and Sweden), and estimate genetically sensitive variance decomposition models. Our comparative design yields three main findings. First, Germany stands out with comparatively weak genetic influences on educational achievement suggesting that early tracking limits the realization thereof. Second, in the United States genetic influences are comparatively strong and similar in size compared to the Nordic countries. Third, in Sweden genetic influences are stronger among disadvantaged families supporting the expectation that challenging and uncertain circumstances promote genetic expression. This ideosyncratic finding must be related to features of Swedish social institutions or welfare-state arrangements that are not found in otherwise similar countries.