title: Persistent Detwinning of Iron-Pnictide EuFe_{2}As_{2} Crystals by Small External Magnetic Fields.
abstract: Our comprehensive study on EuFe_{2}As_{2} reveals a dramatic reduction of magnetic detwinning fields compared to other AFe_{2}As_{2} (A=Ba, Sr, Ca) iron pnictides by indirect magnetoelastic coupling of the Eu^{2+} ions. We find that only ∼0.1  T are sufficient for persistent detwinning below the local Eu^{2+} ordering; above T_{Eu}=19  K, higher fields are necessary. Even after the field is switched off, a significant imbalance of twin domains remains constant up to the structural and electronic phase transition (190 K). This persistent detwinning provides the unique possibility to study the low temperature electronic in-plane anisotropy of iron pnictides without applying any symmetry-breaking external force.
authors.affiliation: 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Zapf
authors.affiliation: I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Stingl
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: K W
authors.initials: KW
authors.lastname: Post
authors.affiliation: I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany and Experimentalphysik VI, Universität Augsburg, Universitätsstraße 1, 86135 Augsburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Maiwald
authors.affiliation: I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Bach
authors.affiliation: I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Pietsch
authors.affiliation: 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Neubauer
authors.affiliation: 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Löhle
authors.affiliation: 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Clauss
authors.affiliation: 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Jiang
authors.affiliation: I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany and Department of Physics, PESITM, Sagar Road, 577204 Shimoga, India.
authors.forename: H S
authors.initials: HS
authors.lastname: Jeevan
authors.affiliation: Department of Physics, University of California, San Diego, La Jolla, California 92093, USA.
authors.forename: D N
authors.initials: DN
authors.lastname: Basov
authors.affiliation: I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany and Experimentalphysik VI, Universität Augsburg, Universitätsstraße 1, 86135 Augsburg, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Gegenwart
authors.affiliation: 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Dressel