Publications (20)
Horndeski Proca stars with vector hair
Y. Brihaye, B. Hartmann, B. Kleihaus +1
We study Proca stars in a vector-tensor gravity model inspired by Horndeski's generalized Einstein-Maxwell field equations, supplemented with a mass term for the vector field. We d…
Multiferroicity in the Mott Insulating Charge-Transfer Salt κ-(BEDT-TTF)Cu[N(CN)]Cl
M. Lang, P. Lunkenheimer, J. Müller +6
The recently proposed multiferroic state of the charge-transfer salt κ-(BEDT-TTF)Cu[N(CN)]Cl [P. Lunkenheimer et al., Nature Mater., vol. 11, pp. 755-758, Sept. 2012] has…
Pathway to the Square Kilometre Array - The German White Paper -
F. Aharonian, T. G. Arshakian, B. Allen +69
The Square Kilometre Array (SKA) is the most ambitious radio telescope ever planned. With a collecting area of about a square kilometre, the SKA will be far superior in sensitivity…
Boson and neutron stars with increased density
Y. Brihaye, L. Ducobu, B. Hartmann
We discuss boson stars and neutron stars, respectively, in a scalar-tensor gravity model with an explicitly time-dependent real scalar field. While the boson stars in our model --…
Inflating branes inside abelian strings
Y. Brihaye, T. Delsate, B. Hartmann
We study a 6-dimensional brane world model with an abelian string residing in the two extra dimensions. We study both static as well as inflating branes and find analytic solutions…
Charged and radially excited boson stars (in Anti-de Sitter)
Y. Brihaye, F. Console, B. Hartmann
We study charged and radially excited boson stars in both asymptotically flat as well as asymptotically Anti-de Sitter space-time. We demonstrate that two different types of radial…
A scalar field instability of rotating and charged black holes in (4+1)-dimensional Anti-de Sitter space-time
Y. Brihaye, B. Hartmann
We study the stability of static as well as of rotating and charged black holes in (4+1)-dimensional Anti-de Sitter space-time which possess spherical horizon topology. We observe…
Dyonic Non-Abelian Black Holes
Y. Brihaye, B. Hartmann, J. Kunz +1
We study static spherically symmetric dyonic black holes in Einstein-Yang-Mills-Higgs theory. As for the magnetic non-abelian black holes, the domain of existence of the dyonic non…
Generalised Wick Transform in Dimensionally Reduced Gravity
B. Hartmann, J. Wisniewski
In the context of canonical quantum gravity, we study an alternative real quantisation scheme, which is arising by relating simpler Riemannian quantum theory to the more complicate…
Critical Slowing Down of the Charge Carrier Dynamics at the Mott Metal-Insulator Transition
B. Hartmann, D. Zielke, J. Polzin +2
We report on the dramatic slowing down of the charge carrier dynamics in a quasi-two-dimensional organic conductor, which can be reversibly tuned through the Mott metal-insulator t…
Mott metal-insulator transition induced by utilizing a glass-like structural ordering in low-dimensional molecular conductors
B. Hartmann, J. Müller, T. Sasaki
We utilize a glass-like structural transition in order to induce a Mott metal-insulator transition in the quasi-two-dimensional organic charge-transfer salt -(BEDT-TTF)Cu[N…
Harmonic Map Analysis of SU(N) Gravitating Skyrmions
Y. Brihaye, B. Hartmann, T. Ioannidou +1
In this paper the SU(N) Einstein-Skyrme system is considered. We express the chiral field (which is not a simple embedding of the SU(2) one) in terms of harmonic maps. In this way,…
Inflation inside non-topological defects and scalar black holes
Y. Brihaye, F. Cônsole, B. Hartmann
In this paper, we demonstrate that a phenomenon described as "topological inflation" during which inflation occurs inside the core of topological defects, has a non-topological cou…
Ferroelectric properties of charge-ordered alpha-(BEDT-TTF)2I3
P. Lunkenheimer, B. Hartmann, M. Lang +4
A detailed investigation of the out-of-plane electrical properties of charge-ordered alpha-(BEDT-TTF)2I3 provides clear evidence for ferroelectricity. Similar to multiferroic alpha…
Multiferroicity in an organic charge-transfer salt: Electric-dipole-driven magnetism
P. Lunkenheimer, J. Müller, S. Krohns +8
Multiferroics, showing simultaneous ordering of electrical and magnetic degrees of freedom, are remarkable materials as seen from both the academic and technological points of view…
Inflating branes inside topological defects and periodic structures
Y. Brihaye, B. Hartmann
We study brane world models which contain local topological defects in the bulk and a (3+1)-dimensional inflating brane. We put the emphasis on new types of solutions that are peri…
Spherically symmetric charged black holes with wavy scalar hair
Y. Brihaye, B. Hartmann
We study standard Einstein-Maxwell theory minimally coupled to a complex valued and self-interacting scalar field. We demonstrate that new, previously unnoticed spherically symmetr…
Gravitating monopole and black holes at intermediate Higgs masses
Y. Brihaye, B. Hartmann, J. Kunz
Self-gravitating SU(2) Higgs magnetic monopoles exist up to a critical value of the ratio of the vector meson mass to the Planck mass, which depends on the Higgs boson mass. At the…
Origin of the glass-like dynamics in molecular metals -(BEDT-TTF)X: implications from fluctuation spectroscopy and calculations
J. Müller, B. Hartmann, R. Rommel +3
We have studied the low-frequency dynamics of the charge carriers in different organic charge-transfer salts -(BEDT-TTF)X with polymeric anions X by using resistance noise…
Black strings in (4+1)-dimensional Einstein-Yang-Mills theory
Y. Brihaye, B. Hartmann, E. Radu
We study two classes of static uniform black string solutions in a (4+1)-dimensional SU(2) Einstein-Yang-Mills model. These configurations possess a regular event horizon and corre…