TY  - JOUR
A1  - Hsu, Pin-Jui
A1  - Kügel, Jens
A1  - Kemmer, Jeannette
A1  - Toldin, Francesco Parisen
A1  - Mauerer, Tobias
A1  - Vogt, Matthias
A1  - Assaad, Fakher
A1  - Bode, Matthias
T1  - Coexistence of charge and ferromagnetic order in fcc Fe
JF  - Nature Communications
N2  - Phase coexistence phenomena have been intensively studied in strongly correlated materials where several ordered states simultaneously occur or compete. Material properties critically depend on external parameters and boundary conditions, where tiny changes result in qualitatively different ground states. However, up to date, phase coexistence phenomena have exclusively been reported for complex compounds composed of multiple elements. Here we show that charge- and magnetically ordered states coexist in double-layer Fe/Rh(001). Scanning tunnelling microscopy and spectroscopy measurements reveal periodic charge-order stripes below a temperature of 130 K. Close to liquid helium temperature, they are superimposed by ferromagnetic domains as observed by spin-polarized scanning tunnelling microscopy. Temperature-dependent measurements reveal a pronounced cross-talk between charge and spin order at the ferromagnetic ordering temperature about 70 K, which is successfully modelled within an effective Ginzburg–Landau ansatz including sixth-order terms. Our results show that subtle balance between structural modifications can lead to competing ordering phenomena.
KW  - ferromagnetism
KW  - phase transitions and critical phenomena
KW  - coexistence
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-173969
VL  - 7
ER  - 
TY  - JOUR
A1  - Sessi, Paolo
A1  - Biswas, Rudro R.
A1  - Bathon, Thomas
A1  - Storz, Oliver
A1  - Wilfert, Stefan
A1  - Barla, Alessandro
A1  - Kokh, Konstantin A.
A1  - Tereshchenko, Oleg E.
A1  - Fauth, Kai
A1  - Bode, Matthias
A1  - Balatsky, Alexander V.
T1  - Dual nature of magnetic dopants and competing trends in topological insulators
JF  - Nature Communications
N2  - Topological insulators interacting with magnetic impurities have been reported to host several unconventional effects. These phenomena are described within the framework of gapping Dirac quasiparticles due to broken time-reversal symmetry. However, the overwhelming majority of studies demonstrate the presence of a finite density of states near the Dirac point even once topological insulators become magnetic. Here, we map the response of topological states to magnetic impurities at the atomic scale. We demonstrate that magnetic order and gapless states can coexist. We show how this is the result of the delicate balance between two opposite trends, that is, gap opening and emergence of a Dirac node impurity band, both induced by the magnetic dopants. Our results evidence a more intricate and rich scenario with respect to the once generally assumed, showing how different electronic and magnetic states may be generated and controlled in this fascinating class of materials.
KW  - magnetic properties and materials
KW  - topological insulators
KW  - magnetic dopants
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-172704
VL  - 7
ER  -