title: Ferromagnetic quantum critical point in the heavy-fermion metal YbNi4(P(1-x)As(x))2.
abstract: Unconventional superconductivity and other previously unknown phases of matter exist in the vicinity of a quantum critical point (QCP): a continuous phase change of matter at absolute zero. Intensive theoretical and experimental investigations on itinerant systems have shown that metallic ferromagnets tend to develop via either a first-order phase transition or through the formation of intermediate superconducting or inhomogeneous magnetic phases. Here, through precision low-temperature measurements, we show that the Grüneisen ratio of the heavy fermion metallic ferromagnet YbNi(4)(P(0.92)As(0.08))(2) diverges upon cooling to T = 0, indicating a ferromagnetic QCP. Our observation that this kind of instability, which is forbidden in d-electron metals, occurs in a heavy fermion system will have a large impact on the studies of quantum critical materials.
authors: Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Strasse 40, 01187 Dresden, Germany. steppke@cpfs.mpg.de
authors: Alexander
authors: A
authors: Steppke
authors: Robert
authors: R
authors: Küchler
authors: Stefan
authors: S
authors: Lausberg
authors: Edit
authors: E
authors: Lengyel
authors: Lucia
authors: L
authors: Steinke
authors: Robert
authors: R
authors: Borth
authors: Thomas
authors: T
authors: Lühmann
authors: Cornelius
authors: C
authors: Krellner
authors: Michael
authors: M
authors: Nicklas
authors: Christoph
authors: C
authors: Geibel
authors: Frank
authors: F
authors: Steglich
authors: Manuel
authors: M
authors: Brando