Quantum critical point scenarios in heavy-fermion systems

重费米子系统中的量子临界点场景

• 批准号: 48554181
• 负责人: Professor Dr. Philipp Gegenwart
• 金额: --
• 依托单位: Max-Planck-Institut für Chemische Physik fester Stoffe (MPI CPfS)
• 依托单位国家: 德国
• 项目类别: Research Units
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2014-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/48554181?language=en
• 关键词: Quantum; critical; point; scenarios; heavy

Different types of heavy-fermion (HF) quantum critical points (QCPs) are investigated by systematic low-temperature experiments on high-quality single crystals. Two kinds of QCPs are known to exist in HF metals: The standard “itinerant” one and the “local” Kondobreakdown QCP where a selective Mott transition of the 4f-electrons is considered at a lowenergy scale T*(H). While CeNi2Ge2 is located very close to a QCP of the former type, YbRh2Si2 displays many features which are described by the latter one. Upon tuning the unitcell volume of YbRh2Si2, by partially substituting Rh with isoelectronic but smaller Co or larger Ir, the energy scale T*(H) remains unchanged whereas the antiferromagnetic (AF) phase is enlarged (Co-doping) or suppressed (Ir-doping). In Ir-doped single crystals a metallic spin-liquid type of ground state emerges, which will be characterized. Metallic spinliquid type behavior will also be investigated in the geometrically frustrated Kondo lattice Pr2Ir2O7. Moreover, we will fine-tune the ground state properties of single crystals of CeNi2Ge2 across the QCP by slight Ni:Ge variation and Pd-doping in Ce(Ni1−xPdx)2Ge2. Finally, ferromagnetic, metamagnetic and antiferromagnetic instabilities in various new 4felectron Ce- and Yb-based HF and also in few 3d-electron metals will be investigated.

通过对高质量单晶的系统低温实验，研究了不同类型的重费米子量子临界点。HF金属中存在两种QCP：标准的“巡回”QCP和“局部”Kondobraftdown QCP，其中4f电子的选择性Mott跃迁被认为是在低能标度T*（H）下。虽然CeNi2Ge2位于非常接近前一种类型的QCP，YbRh2Si2显示了许多功能，后者所描述的。在调整YbRh2Si2的晶胞体积时，通过用等电子但较小的Co或较大的Ir部分取代Rh，能量标度T*（H）保持不变，而反铁磁（AF）相被扩大（Co掺杂）或抑制（Ir掺杂）。在Ir掺杂的单晶中，出现了基态的金属自旋液体类型，其特征在于。金属自旋液体类型的行为也将在几何挫折近藤晶格Pr2Ir2O7进行研究。此外，我们将通过在Ce（Ni1−xPdx）2Ge2中轻微的Ni：Ge变化和Pd掺杂来微调CeNi2Ge2单晶的基态性质。最后，铁磁，变磁和反铁磁不稳定性，在各种新的4f电子Ce和Yb基HF和一些3d电子金属也将进行研究。

项目成果

Avoided ferromagnetic quantum critical point: unusual short-range ordered state in CeFePO.

• DOI: 10.1103/physrevlett.109.216402
• 发表时间: 2012-10
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: S. Lausberg;J. Spehling;A. Steppke;A. Jesche;H. Luetkens;A. Amato;C. Baines;C. Krellner;M. Brando;C. Geibel;H. Klauss;F. Steglich

Quantum bicriticality in the heavy-fermion metamagnet YbAgGe.

• DOI: 10.1103/physrevlett.111.116401
• 发表时间: 2013-06
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: Y. Tokiwa;Markus Garst;P. Gegenwart;S. Bud’ko;P. Canfield

Thermal and electrical transport across a magnetic quantum critical point

• DOI: 10.1038/nature11072
• 发表时间: 2012-04
• 期刊: Nature
• 影响因子: 64.8
• 作者: H. Pfau;S. Hartmann;U. Stockert;P. Sun;S. Lausberg;M. Brando;S. Friedemann;C. Krellner;C. Geibel-C.-G

Ferromagnetic Quantum Critical Point in the Heavy-Fermion Metal YbNi4(P1−xAsx)2

• DOI: 10.1126/science.1230583
• 发表时间: 2013-02
• 期刊: Science
• 影响因子: 56.9
• 作者: A. Steppke;R. Küchler;S. Lausberg;E. Lengyel;L. Steinke;R. Borth;T. Lühmann;C. Krellner;M. Nickla

Detaching the antiferromagnetic quantum critical point from the Fermi-surface reconstruction in YbRh2Si2

• DOI: 10.1038/nphys1299
• 发表时间: 2009-07-01
• 期刊: NATURE PHYSICS
• 影响因子: 19.6
• 作者: Friedemann, S.;Westerkamp, T.;Steglich, F.
• 通讯作者: Steglich, F.