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High mobility in a van der Waals layered antiferromagnetic metal

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Science Advances  07 Feb 2020:
Vol. 6, no. 6, eaay6407
DOI: 10.1126/sciadv.aay6407
  • Fig. 1 GdTe3 crystal structure and antiferromagnetism.

    (A) Illustration of the GdTe3 crystal structure: A vdW gap is located between the two neighboring Te sheets. The rectangular box indicates the unit cell if no CDW is considered. (B) STM image of the GdTe3 surface at 72 K with a tip bias of 0.2 V. The CDW vector is along the b axis. The left inset shows a typical GdTe3 crystal. The right inset shows a zoom-in image with atomic resolution. (C) Temperature-dependent magnetization of a bulk GdTe3 crystal under zero-field cooling conditions. H//c and Hc indicate the applied field perpendicular and parallel to the basal plane, respectively. The arrows indicate the three transitions. Photo credit: Shiming Lei, Princeton University.

  • Fig. 2 QOs of bulk GdTe3.

    (A) dHvA oscillations at 1.8 K with L-K fit. The inset shows the FFT spectrum, with five indicated oscillation frequencies. (B) Temperature dependence of the amplitudes of β1, β2, and γ2 oscillations from dHvA measurements. The solid lines are fits to the L-K formula. (C) SdH oscillations after subtracting the polynomial background from field-dependent resistivity measurements (ρxx) for sample 3. The inset shows the FFT spectrum, with resolved α oscillation and its third harmonics. (D) Temperature dependence of the amplitude of the α oscillation from SdH measurements. The solid line is a fit to the L-K formula above TN, resulting in the effective masses of m*(α)3 and m*(α)4 for samples 3 and 4, respectively.

  • Fig. 3 Carrier concentrations and transport mobilities of bulk GdTe3 and a 22-nm flake.

    (A and B) Temperature-dependent carrier concentrations and mobilities from Hall measurements of bulk GdTe3. The dashed lines indicate TN. (C) Temperature-dependent resistivity on a 22-nm-thin flake, showing both the existence of the CDW and the antiferromagnetic transition. The inset shows the low-temperature resistivity under an applied field of 5 T, revealing the magnetic transition. (D) Temperature-dependent electron and hole mobilities of the 22-nm-thin flake.

  • Fig. 4 Exfoliation of GdTe3 ultrathin flakes.

    (A and B) An AFM image of exfoliated GdTe3 ultrathin flakes and its cross-sectional height profiles. Note that the height profiles are translated into the number of GdTe3 layers on the right vertical axis in (B). One layer corresponds to half a unit cell (shown in Fig. 1A).

  • Table 1 Carrier concentrations and mobilities from Hall measurements.

    The results outside and inside the parentheses are from fits to the Hall resistivity (ρxy) and Hall conductivity (σxy), respectively.

    Sample numberne
    (×1021 cm−3)
    nh
    (×1021 cm−3)
    μt (e) (cm2 V−1 s−1)μt (h) (cm2 V−1 s−1)Sample geometry
    11.05
    (0.61)
    2.53
    (2.03)
    28,100
    (37,700)
    8,300
    (13,500)
    Bulk
    30.96
    (0.62)
    2.41
    (2.02)
    17,700
    (23,300)
    6,000
    (8,400)
    41.07
    (1.15)
    2.70
    (2.75)
    14,000
    (12,000)
    5,100
    (5,400)
    51.59
    (2.28)
    2.74
    (3.43)
    113,000
    (61,200)
    15,000
    (23,500)
    61.01
    (1.12)
    2.15
    (2.05)
    5,700
    (5,400)
    3,300
    (3,300)
    Thin flake
  • Table 2 A compilation of bulk materials with magnetic order, in addition to ZrSiS, PdCoO2, graphite, and black phosphorus, for which high mobilities are reported, in comparison to GdTe3.

    For the transport mobility (μt) estimated from Hall measurement, the values outside and inside the parentheses represent the electron and hole carriers, respectively. For the quantum lifetime–derived mobility (μq) and effective mass (m*) estimated from SdH and dHvA oscillations, a range with lower and upper bounds is provided. For the transport mobility estimated from a combination of the QO and residual resistivity measurements, we denote it as “hybrid.” The transport mobility estimated from MR is listed when it is considered to be more accurate than the Hall mobility. The mobilities of PdCrO2 and PdCoO2 were deduced by the hybrid method because no quantum lifetime or Hall carrier mobility is reported in the literature. The mobility of EuMnBi2 from the hybrid method is also listed for comparison with the Hall carrier mobility. NA, not available.

    Materialμq or μt
    (cm2 V−1 s−1)
    m*/meMethodReference
    SrMnBi22500.29SdH(44)
    CaMnBi24880.53SdH(45)
    Sr1−yMn1−zSb25700.04–0.05SdH(46)
    YbMnBi26890.27SdH(47)
    YbMnSb21,584
    1,072
    6,538 (1,310)
    0.134
    0.108
    NA
    SdH
    dHvA
    Hall
    (48)
    (48)
    (48)
    EuMnBi21.6 (520)
    (14,000)
    NA
    NA
    Hall
    Hybrid
    (49)
    (50)
    BaMnSb21,280
    1,300
    0.052–0.058
    NA
    SdH
    Hall
    (51)
    (51)
    GdPtBiNot reported
    (1,500–2,000)
    0.23
    NA
    SdH
    Hall
    (52)
    (52)
    PdCrO28,7000.33–1.55Hybrid(53)
    BaFe2As2*1,130NAMR(54)
    GdTe31,165–2,012
    >61,200 (>15,000)
    0.101–0.213
    NA
    SdH and dHvA
    Hall
    This work
    ZrSiS1,300–6,200
    4,219–10,000
    20,000 (2,800)
    0.1–0.14
    0.025–0.052
    NA
    SdH
    dHvA
    Hall
    (28)
    (55)
    (28)
    PdCoO251,0001.45–1.53Hybrid(37)
    Graphite1,263,000NAMR(24)
    Black phosphorus(65,000)NAHall(25)

    *The average mobility value from Hall data is 376 cm2 V−1 s−1, but it was considered to be inaccurate. Therefore, the MR was used to evaluate the average mobility.

    †The average mobility is adopted.

    ‡The hole mobility in p-type black phosphorus is adopted as it is higher than the electron mobility n-type one.

    Supplementary Materials

    • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/6/6/eaay6407/DC1

      Section S1. Crystal structure, composition, magnetization, heat capacity, and in-plane resistivity

      Section S2. STM topography and spectroscopy

      Section S3. MR and SdH oscillations

      Section S4. Comparison of the FS pockets from QO measurements to the calculated ones

      Section S5. Carrier concentration estimations from QO measurements versus Hall measurements

      Section S6. ARPES measurement

      Section S7. Air sensitivity study and Raman spectroscopy of GdTe3 thin flakes

      Section S8. Additional notes on mobility for materials shown in Table 2

      Table S1. An overview of the GdTe3 samples (bulk and thin-flake geometries), on which we have performed transport measurements in this work.

      Table S2. Material properties derived from QO measurements.

      Fig. S1. X-ray diffraction pattern, magnetization, and in-plane resistivity measurements on bulk GdTe3 crystals.

      Fig. S2. CDW revealed by STM on a GdTe3 crystal.

      Fig. S3. MR and SdH oscillations.

      Fig. S4. Two-band model fits to the Hall resistivity and conductivity at various temperatures on multiple samples.

      Fig. S5. Temperature-dependent carrier concentrations and mobilities from two-band model fits to the Hall conductivities measured on sample 1.

      Fig. S6. FS measured by ARPES and gap opening by the CDW in GdTe3.

      Fig. S7. Air sensitivity of GdTe3 thin flakes.

      Fig. S8. Raman spectroscopy on a series of GdTe3 thin flakes with varying thicknesses.

      References (5662)

    • Supplementary Materials

      This PDF file includes:

      • Section S1. Crystal structure, composition, magnetization, heat capacity, and in-plane resistivity
      • Section S2. STM topography and spectroscopy
      • Section S3. MR and SdH oscillations
      • Section S4. Comparison of the FS pockets from QO measurements to the calculated ones
      • Section S5. Carrier concentration estimations from QO measurements versus Hall measurements
      • Section S6. ARPES measurement
      • Section S7. Air sensitivity study and Raman spectroscopy of GdTe3 thin flakes
      • Section S8. Additional notes on mobility for materials shown in Table 2
      • Table S1. An overview of the GdTe3 samples (bulk and thin-flake geometries), on which we have performed transport measurements in this work.
      • Table S2. Material properties derived from QO measurements.
      • Fig. S1. X-ray diffraction pattern, magnetization, and in-plane resistivity measurements on bulk GdTe3 crystals.
      • Fig. S2. CDW revealed by STM on a GdTe3 crystal.
      • Fig. S3. MR and SdH oscillations.
      • Fig. S4. Two-band model fits to the Hall resistivity and conductivity at various temperatures on multiple samples.
      • Fig. S5. Temperature-dependent carrier concentrations and mobilities from two-band model fits to the Hall conductivities measured on sample 1.
      • Fig. S6. FS measured by ARPES and gap opening by the CDW in GdTe3.
      • Fig. S7. Air sensitivity of GdTe3 thin flakes.
      • Fig. S8. Raman spectroscopy on a series of GdTe3 thin flakes with varying thicknesses.
      • References (5662)

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